(A) (B) (C) (D) solution: Equation of the curve is ……….(i) Slope of the tangent to curve (i) at any point = Slope of the normal = negative reciprocal = [ Slopes of lines making equal...
Choose the correct answer in:The normal to the curve x ^2 = 4y passing (1,2) is (A) x + y = 3 (B) x – y = 3 (C) x + y = 1 (D) x – y = 1
Equation of the curve is ………..(i) Slope of the normal at = ……….(ii) Again slope of normal at given point (1, 2) = ……….(iii) From eq. (ii) and (iii), we have From eq. (i), ...
Choose the correct answer in: The normal at the point (1,1) on the curve 2y + x ^2 = 3 is (A) x + y = 0 (B) x – y = 0 (C) x + y +1 = 0 (D) x – y = 1
Equation of the given curve is ……….(i) Slope of the tangent to the given curve at point (1, 1) = (say) Slope of the normal = Equation of the normal at (1, 1) is Therefore, The...
Choose the correct answer in: A cylindrical tank of radius 10 m is being filled with wheat at the rate of 314 cubic metre per hour. Then the depth of the wheat is increasing at the rate of (A) 1 m/h (B) 0.1 m/h (C) 1.1 m/h (D) 0.5 m/h
Equation of the curve is ……….(i) Slope of the tangent to the given curve at point = ……….(ii) Now …..(iii) Putting the values of and in eq. (i), Therefore, The correct...
Choose the correct answer in The slope of the tangent to the curve x = t^ 2 + 3t – 8, y = 2t^ 2 – 2t – 5 at the point (2,– 1) is (A) 22/ 7 (B) 6 /7 (C) 7/ 6 (D) -6/ 7
Equation of the curves are …..(i) and …..(ii) and Slope of the tangent to the given curve at point = …..(iii) At the given point and At , from eq. (i), At , from eq. (ii), ...
Choose the correct answer in the questions :A cylindrical tank of radius 10 m is being filled with wheat at the rate of 314 cubic meter per hour. Then the depth of wheat is increasing at the rate of: (A) 1 m/h (B) 0.1 m/h (C) 1.1 m/h (D) 0.5 m/h
Let be the depth of the wheat in the cylindrical tank of radius 10 m at time V = Volume of wheat in cylindrical tank at time cu. m It is given that = 314 cu. m/hr 1 m/h Therefore,The...
Show that height of the cylinder of greatest volume which can be inscribed in a right circular cone of height h and semi vertical angle α is one-third that of the cone and the greatest volume of cylinder is 4 /27πh^3tan^2 α .
Let be the radius of the right circular cone of height Let the radius of the inscribed cylinder be and height In similar triangles APQ and ARC, Volume of cylinder (V) = ……….(ii) V = ...
Show that the height of the cylinder of maximum volume that can be inscribed in a sphere of radius R is 2R/√3 . Also find the maximum volume.
Let be the radius and be the height of the cylinder inscribed in a sphere having centre O and radius R. In right triangle OAM, AM2 + OM2 = OA2 ……….(i) Volume of cylinder (V) = ……….(ii) V...
Let f be a function defined on [a, b] such that f ′(x) > 0, for all x ∈ (a, b). Then prove that f is an increasing function on (a, b).
Let I be the interval Given: for all in an interval I. Let I with By Lagrange’s Mean Value Theorem, we have, where where Now ……….(i) Also, for all in an interval I From eq. (i), ...
Show that the altitude of the right circular cone of maximum volume that can be inscribed in a sphere of radius r is 4r/3
Let be the radius of base of cone and be the height of the cone inscribed in a sphere of radius OD = AD – AO = In right angled triangle OBD, OD2 + BD2 = OB2 ……….(i) Volume of cone (V)...
Find the absolute maximum and minimum values of the function f given by f (x) = cos^2 x + sin x, x ∈ [0, π]
……….(i) = = Now = 0 or or [Turning points] Now = 0 + 1 = 1 1 + 0 = 1 = 1 Therefore, absolute maximum is and absolute minimum is...
Find the points at which the function f given by f (x) = (x – 2)^4 (x + 1)^3 has (i) local maxima (ii) local minima (iii) point of inflexion.
Given: ……….(i) = = = Now = 0 or or or or Now, for values of close to and to the left of . Also for values of close to and to the right of . Therefore, is the point of local maxima....
A point on the hypotenuse of a triangle is at distance a and b from the sides of the triangle. Show that the minimum length of the hypotenuse is (a^2/3+b^2/3)^3/2
Let P be a point on the hypotenuse AC of a right triangle ABC such that PL AB = and PM BC = and let BAC = MPC = , then in right angled AP = PL = And in right angled PMC, PM = PM Let AC = then...
A window is in the form of a rectangle surmounted by a semicircular opening. The total perimeter of the window is 10 m. Find the dimensions of the window to admit maximum light through the whole opening.
Let m be the radius of the semi-circular opening of the window. Then one side of rectangle part of window is and m be the other side of rectangle. Perimeter of window = Semi-circular arc AB +...
The sum of the perimeter of a circle and square is k, where k is some constant. Prove that the sum of their areas is least when the side of square is double the radius of the circle
Let be the radius of the circle and be the side of square. According to question, Perimeter of circle + Perimeter of square = ……….(i) Let be the sum of areas of circle and square. [From...
A tank with rectangular base and rectangular sides, open at the top is to be constructed so that its depth is 2 m and volume is 8 m^3 . If building of tank costs Rs 70 per sq metres for the base and Rs 45 per square metre for sides. What is the cost of least expensive tank?
Given: Depth of tank = 2 m Let m be the length and m be the breadth of the base of the tank. Volume of tank = 8 cubic meters Cost of building the base of the tank at the rate of ` 70 per sq....
Find the maximum area of an isosceles triangle inscribed in the ellipse x^2/a^2+^2/b^2 with its vertex at one end of the major axis.
Equation of the ellipse is ……….(i) Comparing eq. (i) with we have and and Any point on ellipse is P Draw PM perpendicular to axis and produce it to meet the ellipse in the point Q. OM = and...
Find the intervals in which the function f given by f ( x)=x^3+1/x^3 , x≠0 is (i) increasing (ii) decreasing.
= = = ……….(i) Now = 0 = 0 Here, is positive for all real or [Turning points] Therefore, or divide the real line into three sub intervals and For , from eq. (i) at (say),...
Find the intervals in which the function f given by f(x)=4sinx-2x-xcosx/2+cosx is (i) increasing (ii) decreasing.
= = = = = = = ……….(i) Now for all real as . Also > 0 (i) is increasing if , i.e., from eq. (i), lies in I and IV quadrants, i.e., is increasing for and and (ii) is decreasing...
Show that the normal at any point θ to the curve x = a cosθ + a θ sin θ, y = a sinθ – aθ cosθ is at a constant distance from the origin.
The parametric equations of the curve are And Slope of tangent at point = Slope of normal at any point = And Equation of normal at any point i.e., at = is Distance of normal...
Find the equation of the normal to curve x^2 = 4y which passes through the point (1, 2).
Equation of the curve is ……….(i) Slope of the tangent to the curve at the point (1, 2) to curve (i) is =1 Slope of the normal to the curve at (1, 2) is Equation of the normal to the curve (i)...
The two equal sides of an isosceles triangle with fixed base b are decreasing at the rate of 3 cm per second. How fast is the area decreasing when the two equal sides are equal to the base ?
Let BC = be the fixed base and AB = AC = be the two equal sides of given isosceles triangle. Since cm/s ……….(i) Area of x BC x AM = = = [By chain rule] = cm2/s Now when cm2/s Therefore,...
Show that the function given by f(x)=log (x )/ x has maximum at x = e.
Here ……….(i) ……..(ii) And = ……….(iii) Now From eq. (iii), = = < 0 is a point of local maxima and maximum value of is...
Using differentials, find the approximate value of each of the following: (a) (17/81)^1/4 (b) 33^(-1/3)
Assume ……….(i) = ……….(ii) Changing to and to in eq. (i), we have ……….(iii) Here and From eq. (iii), 0.677 (b) Let ……….(i) = ……….(ii) Changing to and to in eq. (i), we have...
The maximum value of [x(x-1)+1]^1/3, 0≤x≤1 is (A) (1/3)^1/3 (B) 1/2 (C) 1 (C) 1/3
Let = , ……….(i) = Now = 0 [Turning point] and it belongs to the given enclosed interval i.e., [0, 1]. At , from eq. (i), At from eq. (i), At , from eq. (i), Maximum value...
For all real values of x, the minimum value of 1-x+x^2/1+x+x^2 is (A) 0 (B) 1 (C) 3 (D) 1/ 3
Given: ……….(i) = Now = 0 and [Turning points] At , from eq. (i), At , from eq. (i), [Minimum value] Therefore, The correct option is option...
Choose the correct answer The point on the curve x^ 2 = 2y which is nearest to the point (0, 5) is (A) (2 2,4) (B) (2 2,0) (C) (0, 0) (D) (2, 2)
Equation of the curve is ……….(i) Let P be any point on the curve (i), then according to question, Distance between...
Show that semi-vertical angle of right circular cone of given surface area and maximum volume is sin^−1(1/3) .
Let be the radius and be the height of the cone and semi-vertical angle be Total Surface area of cone (S) = (say) ……….(i) Volume of cone (V) = = = = [Using quotient rule]...
Show that the semi-vertical angle of the cone of the maximum value and of given slant height is tan ^−1√2
Let be the radius, be the height, be the slant height of given cone and be the semi-vertical angle of cone. ……….(i) Volume of the cone (V) = ……….(ii) V = = and Now ...
Show that the right circular cone of least curve surface and given volume has an altitude equal to time the radius of the base.
Let be the radius and be the height of the cone. Volume of the cone (V) = (say) ……….(i) And Surface area of the cone (S) = (say) ….(ii) = = and Now ……….(iii)...
Prove that the volume of the largest cone that can be inscribed in a sphere of radius R is of the volume of the sphere.
Let O be the centre and R be the radius of the given sphere, BM = and AM = In right angled triangle OMB, using Pythagoras theorem, OM2 + BM2 = OB2 ……….(i) Volume of a cone inscribed in...
A wire of length 28 m is to be cut into two pieces. One of the pieces is to be made into a square and the other into a circle. What should be the length of the two pieces so that the combined area of the square and the circle is minimum?
Let meters be the side of square and meters be the radius of the circle. Length of the wire = Perimeter of square + Circumference of circle = 28 ……….(i) Area of square = and Area of...
Of all the closed cylindrical cans (right circular), of a given volume of 100 cubic centimeters, find the dimensions of the can which has the minimum surface area.
Let be the radius of the circular base and be the height of closed right circular cylinder. According to the question, Volume of the cylinder …(i) Total surface area (S) = = = [From eq....
Show that the right circular cylinder of given surface and maximum volume is such that its height is equal to the diameter of the base.
Let be the radius of the circular base and be the height of closed right circular cylinder. Total surface area (S) = = (say) …..(i) Volume of cylinder = [From eq. (i)] and Now ...
Show that of all the rectangles inscribed in a given fixed circle, the square has the maximum area.
Let PQRS be the rectangle inscribed in a given circle with centre O and radius Let and be the length and breadth of the rectangle, i.e., and In right angled triangle PQR, using Pythagoras...
A rectangular sheet of tin 45 cm by 24 cm is to be made into a box without top, by cutting off square from each corner and folding up the flaps. What should be the side of the square to be cut off so that the volume of the box is maximum ?
Dimensions of rectangular sheet are 45 cm and 24 cm. Let cm be the side of each of the four squares cut off from each corner. Then dimensions of the open box formed by folding the flaps after...
A square piece of tin of side 18 cm is to be made into a box without top, by cutting a square from each corner and folding up the flaps to form the box. What should be the side of the square to be cut off so that the volume of the box is the maximum possible.
Each side of square piece of tin is 18 cm. Let cm be the side of each of the four squares cut off from each corner. Then dimensions of the open box formed by folding the flaps after cutting off...
Find two positive numbers whose sum is 16 and the sum of whose cubes is minimum.
Let the two positive numbers are and ……….(i) Let [From eq. (i)] = and Now = 0 At is positive. is a point of local minima and is minimum when . Therefore, the...
Find two positive numbers x and y such that their sum is 35 and the product x ^2 y^ 5 is a maximum.
Given: ……….(i) Let [From eq. (i)] ……….(ii) Now or or or or Now is rejected because according to question, is a positive number. Also is rejected because from eq....
Find two positive numbers x and y such that x + y = 60 and xy^3 is maximum.
Given: ……….(i) Let P = [To be maximized] ……….(ii) Putting from eq. (i), in eq. (ii), P = …..(iii) Now It is clear that changes sign from positive to negative as increases...
Find two numbers whose sum is 24 and whose product is as large as possible
Let the two numbers be and According to the question, …….(i) And let is the product of and [From eq. (i)] and Now to find turning point, At , [Negative] is a point of...
Find the maximum and minimum values of x + sin 2x on [0, 2π]
Let Now = = = where Z For But , therefore For = and For But , therefore Therefore, it is clear that the only turning point of given by which belong to given closed...
It is given that at x = 1, the function x^ 4 – 62x^ 2 + ax + 9 attains its maximum value, on the interval [0, 2]. Find the value of a.
Let Since, attains its maximum value at in the interval [0, 2], therefore
Find the maximum value of 2x ^3 – 24x + 107 in the interval [1, 3]. Find the maximum value of the same function in [–3, –1].
Let Now or [Turning points] For Interval [1, 3], is turning point. At At At Therefore, maximum value of is 89. For Interval is turning point. At At At Therefore,...
What is the maximum value of the function sin x + cos x?
Let Now = [Turning point] = = = = If is even, then If is odd, then Therefore, maximum value of is and minimum value...
At what points in the interval [0, 2π], does the function sin 2x attain its maximum value?
Let Now Putting Now = = = Putting Also and Since attains its maximum value 1 at and Therefore, the required points...
Find both the maximum value and the minimum value of 3x ^4 – 8x^ 3 + 12x ^2 – 48x + 25 on the interval [0, 3].
Let on [0, 3] Now or Since is imaginary, therefore it is rejected. is turning point. At = At At Therefore, absolute minimum value is and absolute maximum value is...
Find the maximum profit that a company can make, if the profit function is given by p(x) = 41 – 72x – 18x^ 2
Profit function and Now At , [Negative] has a local maximum value at . At , Maximum profit = = 41 + 16 – 8 = 49
Find the absolute maximum value and the absolute minimum value of the following functions in the given intervals: (iii) f (x) = 4x-1/2x^2, x∈[-2,9/2] (iv) f(x)=(x-1)^2+3, x∈[-3,1]
(iii) Given: Now At At At Therefore, absolute minimum value is and absolute maximum value is 8. (iv) Given: Now At At Therefore, absolute minimum value is and absolute...
Find the absolute maximum value and the absolute minimum value of the following functions in the given intervals: (i) f(x) = x^ 3 , x ∈ [– 2, 2] (ii) f (x) = sin x + cos x , x ∈ [0, π]
(i) Given: Now At At At Therefore, absolute minimum value of is and absolute maximum value is 8. (ii) Given: Now [Positive] is in I quadrant. [ ] Therefore,...
Prove that the following functions do not have maxima or minima:(iii) h (x) = x^ 3 + x^ 2 + x +1
(iii) Given: Now = = Here, values of are imaginary. does not have maxima or minima.
Prove that the following functions do not have maxima or minima: (i) f(x) = e^ x (ii) g(x) = log x
(i) Given: Now But this gives no real value of Therefore, there is no turning point. does not have maxima or minima. (ii) Given: Now 1 = 0 But this is not possible. Therefore,...
Find the local maxima and local minima, if any, of the following functions. Find also the local maximum and the local minimum values, as the case may be:(vii) g(x)=1/(x^2+2) (viii) f (x )=x√1- x , 0 <x<1
(vii) Given: and = Now [Turning point] At [Negative] is a point of local maxima and local maximum value is (viii) Given: = = = And = = Now = 0 is a point of...
Find the local maxima and local minima, if any, of the following functions. Find also the local maximum and the local minimum values, as the case may be:(v) f(x) = x ^3 – 6x^ 2 + 9x + 15 (vi) x/2+2 /x , x>0
(v) Given: and Now or [Turning points] At [Negative] is a point of local maxima and local maximum value is At [Positive] is a point of local minima and local minimum...
Find the local maxima and local minima, if any, of the following functions. Find also the local maximum and the local minimum values, as the case may be: (iii) h(x) = sin x + cos x, 0 2 x π < < (iv) f(x) = sin x – cos x, 0 2 < < π
(iii) Given: ……….(i) and Now [Positive] can have values in both I and III quadrant. But, therefore, is only in I quadrant. = [Turning point] At = ...
Find the local maxima and local minima, if any, of the following functions. Find also the local maximum and the local minimum values, as the case may be: (i) f(x) = x ^2 (ii) g(x) = x^ 3 – 3x
(i) Given: and Now [Turning point] Again, when , [Positive] Therefore, is a point of local minima and local minimum value = (ii) Given: and Now or [Turning...
Find the maximum and minimum values, if any, of the following functions given by (v) h(x) = x + 1, x ∈ (– 1, 1)
(v) Given: ……….(i) Since Adding 1 to both sides, Therefore, neither minimum value not maximum value of exists.
Find the maximum and minimum values, if any, of the following functions given by (iii) h(x) = sin(2x) + 5 (iv) f(x) = |sin 4x + 3|
(iii) Given: ……….(i) Since for all R Adding 5 to all sides, Therefore, minimum value of is 4 and maximum value is 6. (iv) Given: Since for all R Adding 3 to all sides, ...
Find the maximum and minimum values, if any, of the following functions given by (iii) f(x) = – (x – 1)^2 + 10 (iv) g(x) = x ^3 + 1
(iii) Given: ……….(i) Since for all R Multiplying both sides by and adding 10 both sides, [Using eq. (i)] Therefore, maximum value of is 10 which is obtained when i.e., And therefore,...
Find the maximum and minimum values, if any, of the following functions given by (i) f (x) = (2x – 1)^2 + 3 (ii) f(x) = 9x ^2 + 12x + 2
(i) Given: Since for all R Adding 3 both sides, Therefore, the minimum value of is 3 when , i.e., This function does not have a maximum value. (ii) Given: = ……….(i)...
The approximate change in the volume of a cube of side x metres caused by increasing the side by 3% is (A) 0.06 x^ 3 m^3 (B) 0.6 x ^3 m^3 (C) 0.09 x ^3 m^3 (D) 0.9 x ^3 m^3
Since Volume (V) = ……….(i) ……….(ii) It is given that increase in side = 3% = ……….(iii) Since approximate change in volume V of cube = = = cubic meters Therefore,The correct option is ...
If f(x) = 3x^ 2 + 15x + 5, then the approximate value of f (3.02) is (A) 47.66 (B) 57.66 (C) 67.66 (D) 77.66
Let ……….(i) ……….(ii) Changing to and to in eq. (i), = ……….(iii) Here, and From eq. (iii), Since, and is approximately equal to and respectively. From eq. (i) and (ii), = = ...
If the radius of a sphere is measured as 9 m with an error of 0.03 m, then find the approximate error in calculating its surface area.
Let be the radius of the sphere. Surface area of the sphere (S) = · = square meters
If the radius of a sphere is measured as 7 m with an error of 0.02 m, then find the approximate error in calculating its volume.
Let be the radius of the sphere and be the error in measuring the radius. Then, according to the question, = 7 m and = 0.02 m Volume of sphere (V) = Approximate error in calculating the...
Find the approximate change in the surface area of a cube of side x metres caused by decreasing the side by 1%.
Since Surface area (S) = It is given that decrease in side = of Since approximate change in surface area S of cube = = = square meters (decreasing)
Find the approximate change in the volume V of a cube of side x metres caused by increasing the side by 1%.
Since Volume (V) = ……….(i) ……….(ii) It is given that increase in side = 1% = ……….(iii) Since approximate change in volume V of cube = = = cubic...
Find the approximate value of f (5.001), where f(x) = x ^3 – 7x^ 2 + 15.
Let ……….(i) ……….(ii) Changing to and to in eq. (i), = ……….(iii) Here, and From eq. (iii), Since, and is approximately equal to and respectively. From eq. (i) and (ii), = = ...
Find the approximate value of f(2.01), where f (x) = 4x ^2 + 5x + 2.
Let ……….(i) = ……….(ii) Changing to and to in eq. (i), = ……….(iii) Here, and From eq. (iii), Since, and is approximately equal to and respectively. From eq. (i) and (ii), ...
Using differentials, find the approximate value of each of the following up to 3 places of decimal. (xv) (32.15)^1/5
(xv) Let ……….(i) = ……….(ii) Now, from eq. (i), = = ……….(iii) Here and Then = = Since, and is approximately equal to and respectively. From eq. (ii), = 0.001875 Therefore,...
Using differentials, find the approximate value of each of the following up to 3 places of decimal. (xiii) (81.5)^1/4 (xiv) (3.968)^3/2
(xii) Let ……….(i) = ……….(ii) Now, from eq. (i), = = ……….(iii) Here and Then = = Since, and is approximately equal to and respectively. From eq. (ii), = 0.00462 Therefore,...
Using differentials, find the approximate value of each of the following up to 3 places of decimal. (xi) (0.0037)^1/2 (xii) (26.57)^1/3
(xi) Let ……….(i) = ……….(ii) Now, from eq. (i), = Here, and , then = Since, and is approximately equal to and respectively. From eq. (ii), = Therefore, approximately value...
Using differentials, find the approximate value of each of the following up to 3 places of decimal. (ix) (82)^1/4 (x) (401)^1/2
(ix) Let ……….(i) = ……….(ii) Now, from eq. (i), = = ……….(iii) Here and Then = = Since, and is approximately equal to and respectively. From eq. (ii), Therefore, approximate...
Using differentials, find the approximate value of each of the following up to 3 places of decimal. (vii) (26)^1/3 (viii) (255)^1/4
(vii) Let ……….(i) = ……….(ii) Now, from eq. (i), = Here, and , then = Since, and is approximately equal to and respectively. From eq. (ii), = Therefore, approximately value...
Using differentials, find the approximate value of each of the following up to 3 places of decimal. (v) (0.999)^1/10 (vi) (15)^1/4
(v) Let ……….(i) = ……….(ii) Now, from eq. (i), = = ……….(iii) Here and Then = = Since, and is approximately equal to and respectively. From eq. (ii), Therefore, approximate...
Using differentials, find the approximate value of each of the following up to 3 places of decimal.(iii) √0.6 (iv) ∛(0.009)
(iii) Let ……….(i) = ……….(ii) Now, from eq. (i), = Here, and , then = Since, and is approximately equal to and respectively. From eq. (ii), = Therefore, approximately value...
Using differentials, find the approximate value of each of the following up to 3 places of decimal. (i)√ 25.3 (ii) √49.5
Assume ……….(i) = ……….(ii) Now, from eq. (i), = Here, and , then = Since, and is approximately equal to and respectively. From eq. (ii), = 0.03 Therefore, approximately value...
Choose the correct answer: The line y = x + 1 is a tangent to the curve y^ 2 = 4x at the point (A) (1, 2) (B) (2, 1) (C) (1, – 2) (D) (– 1, 2)
Given: Equation of the curve ……….(i) Slope of the tangent at point is ……….(ii) Slope of the line is ……….(iii) From eq. (ii) and (iii), From eq. (i), Therefore, required point is (1,...
Choose the correct answer in: The slope of the normal to the curve y = 2x^ 2 + 3 sin x at x = 0 is (A) 3 (B) 1/ 3 (C) –3 (D)- 1/ 3
Given: Equation of the curve ……….(i) Slope of the tangent at point is Slope of the tangent at (say) Slope of the normal = Therefore,The correct option is option (D)...
Find the equation of the tangent to the curve (fig 1)which is parallel to the line 4x- 2y+ 5= 0
fig 1: SOLUTION: Given: Equation of the curve ……….(i) Slope of the tangent at point is = ……….(ii) Again slope of the line is ……….(iii) According to the question, [Parallel lines have same...
Find the equations of the tangent and normal to the hyperbola x^2/a^2 + y^2/ b^2 =1 at the point (x0 , y0 ).
Given: Equation of the hyperbola ……….(i) ……….(ii) Slope of tangent at is Equation of the tangent at is ……….(iii) Since lies on the hyperbola (i), therefore, From eq....
Prove that the curves x = y ^2 and xy = k cut at right angles if 8k ^2 = 1.
Given: Equations of the curves are …..(i) and ……….(ii) Substituting the value of in eq. (ii), we get Putting the value of in eq. (i), we get Therefore, the point of intersection is...
Find the equations of the tangent and normal to the parabola y^ 2 = 4ax at the point (at^2 , 2at).
Given: Equation of the parabola ……….(i) Slope of the tangent at = Slope of the tangent at the point = Slope of the normal = Equation of the tangent at the point = And Equation...
Find the equation of the normals to the curve y = x ^3 + 2x + 6 which are parallel to the line x + 14y + 4 = 0.
Equation of the curve ….(i) Slope of the tangent at = Slope of the normal to the curve at = ……….(ii) But Slope of the normal (given) = = From eq. (i), at at Therefore, the...
Find the equation of the normal at the point (am^2 ,am^3 ) for the curve ay^2 = x ^3
Equation of the curve ……….(i) Slope of the tangent at the point = = Slope of the normal at the point = Equation of the normal at = ...
Find the points on the curve x ^2 + y ^2 – 2x – 3 = 0 at which the tangents are parallel to the x-axis.
Equation of the curve ……….(i) [tangent is parallel to axis] From eq. (i), Therefore, the required points are (1, 2) and
For the curve y = 4x^ 3 – 2x ^5 , find all the points at which the tangent passes through the origin.
Given: Equation of the curve ……….(i) Slope of the tangent at passing through origin (0, 0) = = Substituting this value of in eq. (i), we get, or or From eq. (i), at From eq....
Find the points on the curve y = x ^3 at which the slope of the tangent is equal to the y-coordinate of the point.
Given: Equation of the curve ………(i) Slope of tangent at = ……….(ii) According to question, Slope of the tangent = coordinate of the point or or From eq. (i), at The point is (0,...
Show that the tangents to the curve y = 7x ^3 + 11 at the points where x = 2 and x = – 2 are parallel.
Equation of the curve Slope of tangent at = At the point Slope of the tangent = At the point Slope of the tangent = Since, the slopes of the two tangents are equal. Therefore, tangents...
Find the equation of the tangent line to the curve y = x^ 2 – 2x +7 which is (a) parallel to the line 2x – y + 9 = 0 (b) perpendicular to the line 5y – 15x = 13
Given: Equation of the curve ……….(i) Slope of tangent = …….(ii) (a) Slope of the line is Slope of tangent parallel to this line is also = 2 From eq. (ii), From eq. (i), Therefore,...
Find the equations of the tangent and normal to the given curves at the indicated points:(v) x = cost, y = sin t at t= π/4
Equation of the curves are and Slope of the tangent at = (say) Slope of the normal at is Point = = = Equation of the tangent is And Equation of the normal is ...
Find the equations of the tangent and normal to the given curves at the indicated points: (iii) y = x ^3 at (1, 1) (iv) y = x ^2 at (0, 0)
Equation of the curve ……….(i) Now value of at (1, 1) At = (say) Slope of the normal at (1, 1) is Equation of the tangent at (1, 1) is And Equation of the normal at (1, 1) is ...
Find the equations of the tangent and normal to the given curves at the indicated points: (i) y = x ^4 – 6x^ 3+ 13x^ 2 –10x + 5 at (0, 5) (ii) y = x ^4 – 6x ^3 + 13x ^2 – 10x + 5 at (1, 3)
(i) Equation of the curve Now value of at (0, 5) At (say) Slope of the normal at (0, 5) is Equation of the tangent at (0, 5) is And Equation of the normal at (0, 5) is ...
Find points on the curve x^ 2/9+ y^2/16=1 at which the tangents are (i) parallel to x-axis (ii) parallel to y-axis
Given: Equation of the curve ……….(i) ……….(ii) (i) If tangent is parallel to axis, then Slope of tangent = 0 = 0 From eq. (i), Therefore, the points on curve (i) where...
Find the equations of all lines having slope 0 which are tangent to the curve y= 1/( x^2-2x+3)
Given: Equation of the curve ……….(i) = = But according to question, slope = 0 = 0 From eq. (i), Therefore, the point on the curve which tangent has slope 0 is Equation of the tangent...
Find the equation of all lines having slope 2 which are tangents to the curve y=1 /(3-x) , x ≠ 3
Given: Equation of the curve = = Slope of the tangent at But according to question, slope = = 2 which is not possible. Hence, there is no tangent to the given curve having slope...
Find the equation of all lines having slope – 1 that are tangents to the curve y= 1 /(1-x) , x ≠ 1.
Given: Equation of the curve ……….(i) = = Slope of the tangent at But according to question, slope = = or From eq. (i), when And when Points of contact are (2, 1) and And...
Find the point on the curve y = x^ 3 – 11x + 5 at which the tangent is y = x – 11.
Given: Equation of the curve ……….(i) Equation of the tangent ……….(ii) From eq. (i), = Slope of the tangent at But from eq. (ii), the slope of tangent = From eq. (i), when And when ...
Find a point on the curve y = (x – 2)^2 at which the tangent is parallel to the chord joining the points (2, 0) and (4, 4).
Let the given points are A (2, 0) and B (4, 4). Slope of the chord AB = Equation of the curve is Slope of the tangent at = If the tangent is parallel to the chord AB, then Slope of tangent =...
Find points at which the tangent to the curve y = x ^3 – 3x^ 2 – 9x + 7 is parallel to the x-axis.
Given: Equation of the curve ……….(i) Since, the tangent is parallel to the axis, i.e., From eq. (i), when when Therefore, the required points...
Find the slope of the normal to the curve x=1-asinθ, y=bcos^2θ at θ=π/2
Given: Equations of the curves are and and and = Slope of the tangent at = And Slope of the normal at = =
Find the slope of the normal to the curve x=acos^3thetha, y=asin^3thetha at thetha=pi/4
Given: Equations of the curves are and = and and = Slope of the tangent at = And Slope of the normal at = = 1
Find the slope of tangent to the curve y= x^3-3x+2 at the given point whose coordinate is 3.
Given: Equation of the curve ……….(i) Slope of the tangent at point to the curve (i) = = 27 – 3 = 24
Find the slope of tangent to the curve y=x^3-x+1 at the given point whose x-coordinate is 2.
Given: Equation of the curve ……….(i) Slope of the tangent at point to the curve (i) = = 12 – 1 = 11
Find the slope of tangent to the curve y=(x-1)/(x+1),x not equal to 0 at x=10
Given: Equation of the curve ……….(i) = = ……….(ii) Slope of the tangent at point to the curve (i) = =
Find the slope of tangent to the curve y=3x^4-4x at x=4
Equation of the curve ……….(i) Slope of the tangent to the curve = Value of at the point Slope of the tangent at point to the curve (i) = = 768 – 4 = 764
Prove that the function f given by f(x)=x^2-x+1 is neither strictly increasing nor strictly decreasing on (-1,1)
Given: is strictly increasing if i.e., increasing on the interval is strictly decreasing if i.e., decreasing on the interval hence, is neither strictly increasing nor decreasing on...
Which of the following functions are strictly decreasing on (0,pi/2)
(C) (D) SOLUTION: (C) Since For Therefore, is strictly decreasing on For Therefore, is strictly increasing on Hence, is neither strictly increasing not strictly decreasing...
Which of the following functions are strictly decreasing on (0,pi/2)
(A) (B) SOLUTION: (A) Since in therefore Therefore, is strictly decreasing on (B) Since therefore Therefore, is strictly decreasing...
On which of the following intervals is the function f given by f(x)=x^100+sinx-1 is strictly decreasing:
(A) (0, 1) (B) (C) (D) None of these SOLUTION: Given: (A) On (0, 1), therefore And for (0, 1 radian) = > 0 Therefore, is strictly increasing on (0, 1). (B) For = = (1.5,...
Find the least value of a such that the function f given by f(x)=x^2+ax+1 strictly increasing on (1, 2).
Since is strictly increasing on (1, 2), therefore > 0 for all in (1, 2) On (1, 2) Minimum value of is and maximum value is Since > 0 for all in (1, 2) and and ...
Let I be any interval disjoint from [-1,1] Prove that the function f given by f(x)=x+1/x is strictly increasing on I.
Given: ……….(i) Here for every either or for , (say), > 0 And for , (say), > 0 > 0 for all , hence is strictly increasing on...
Prove that the function f given by f(x)=logsinx is strictly increasing on (0,pi/2) and strictly decreasing on (pi/2,pi)
Given: On the interval i.e., in first quadrant, > 0 Therefore, is strictly increasing on . On the interval i.e., in second quadrant, < 0 Therefore, is strictly decreasing...
Prove that the function f given by f(x)=logcosx is strictly decreasing on (0,pi/2) and strictly decreasing on (pi/2,pi)
Given: On the interval i.e., in first quadrant, is positive, thus < 0 Therefore, is strictly decreasing on . On the interval i.e., in second quadrant, is negative thus > 0...
Prove that the function given by f(x)=x^3-3x^2+3x-100 is increasing in R.
Given: for all in R. Therefore, is increasing on R.
The interval in which y=x^2e^(-x) is increasing in:
(A) (B) (C) (D) (0, 2) SOLUTION: Given: = = In option (D), for all in the interval (0, 2). Therefore, THE CORRECT OPTION IS option...
Prove that the logarithmic function is strictly increasing on (0,INFINITY)
Given: for all in Therefore, is strictly increasing on
Prove that (fig 1) is an increasing function of theta in [0,pi/2]
fig 1: SOLUTION: = = = = Since and we have , therefore for Hence, is an increasing function of in
Find the value of x for which y={x(x-2)}^2 is an increasing function.
Given: [Applying Product Rule] = = ……….(i) Therefore, we have For taking (say), is decreasing. For taking (say), is increasing. For taking (say), is decreasing....
Show that (fig1) is an increasing function of x throughout its domain.
fig 1: solution: Given: = = = = ……….(i) Domain of the given function is given to be Also and From eq. (i), for all in domain and is an increasing...
Find the intervals in which the following functions are strictly increasing or decreasing:
(e) SOLUTION: (e) Given: Here, factors and are non-negative for all Therefore, is strictly increasing if And is strictly decreasing if Hence, is strictly increasing...
Find the intervals in which the following functions are strictly increasing or decreasing:
(c) (d) SOLUTION: (c) Given: = ……….(i) Now = 0 or Therefore, we have three disjoint intervals and For interval , from eq. (i), = < 0 Therefore, is strictly decreasing. For...
Find the intervals in which the following functions are strictly increasing or decreasing:
(a) (b) SOLUTION: (a) Given: ……….(i) Now Therefore, we have two sub-intervals and For interval taking (say), from eq. (i), < 0 Therefore, is strictly decreasing. For...
Find the intervals in which the function f given by f(x)=2x^3-3x^2-36x+7 is (a) strictly increasing, (b) strictly decreasing.
(a) Given: = ……….(i) Now or or Therefore, we have sub-intervals are and For interval taking (say), from eq. (i), > 0 Therefore, is strictly increasing in For...
Find the intervals in which the function f given by f(x)=2x^2-3x is (a) strictly increasing, (b) strictly decreasing.
Given: ……….(i) Now Therefore, we have two intervals and (a) For interval taking (say), then from eq. (i), > 0. Therefore, is strictly increasing in (b) For...
Show that the function given by f(x)=sinx is (a) strictly increasing (0,pi/2) (b) strictly decreasing (pi/2,pi) in (c) neither increasing nor decreasing in (0,pi)
Given: (a) Since, > 0, i.e., positive in first quadrant, i.e., in Therefore, is strictly increasing in (b) Since, < 0, i.e., negative in second quadrant, i.e., in Therefore, is...
Show that the function given by f(x)=e^2x is strictly increasing on R.
Given: = > 0 i.e., positive for all R Therefore, is strictly increasing on R.
Show that the function given by f(x)=3x+17 is strictly increasing on R.
Given: i.e., positive for all R Therefore, is strictly increasing on R.
Choose the correct answer: The rate of change of the area of a circle with respect to its radius r at r=6 cm is:
(A) (B) (C) (D) SOLUTION: Area of circle (A) = = Therefore, The correct option is option (B) .
The total revenue in rupees received from the sale of x units of a product is given by R(x)= 13x^2+26x +15 Find the marginal revenue when x=7
Marginal Revenue (MR) = = = Now, when MR = 26 x 7 + 26 = 208 Therefore, the required marginal revenue is ` 208.
The total cost C(x) in rupees associated with the production of units of an item given by C (x)= 0.007x^3-0.003x^2-15x+4000 Find the marginal cost when 17 units are produced.
Marginal cost = = = Now, when MC = = 6.069 – 0.102 + 15 = 20.967 Therefore, required Marginal cost is ` 20.97.
Sand is pouring from a pipe at the rate of 12 cm3/s. The falling sand forms a cone on the ground in such a way that the height of the cone is always one-sixth of the radius of the base. How fast is the height of the sand cone increasing when the height is 4cm?
Let the height and radius of the sand-cone formed at time second be cm and cm respectively. According to question, Volume of cone (V) = = = Now, since ...
A balloon which always remains spherical, has a variable diameter 3/2(2x+1) Find the rate of change of its volume with respect to x
Given: Diameter of the balloon = Radius of the balloon = Volume of the balloon = = cu. units Rate of change of volume w.r.t. = = = =
The radius of an air bubble is increasing at the rate of cm/s. At what rate is the volume of the bubble increasing when the radius is 1 cm?
Let cm be the radius of the air bubble at time According to question, is positive = cm/sec ……….(i) Volume of air bubble = = = Therefore, required rate of increase of volume of air bubble...
A particle moves along the curve Find the points on the curve 6y=x^3+2at which the y-coordinate is changing 8 times as fast as the x-coordinate.
Given: Equation of the curve ……….(i) Let be the required point on curve (i) According to the question, ……….(ii) From eq. (i), [From eq. (ii)] Taking Required point is (4, 11)....
A ladder 5 cm long is leaning against a wall. The bottom of the ladder is pulled along the ground, away from the wall, at the rate of 2 cm/s. How fast is its height on the wall decreasing when the foot of the ladder is 4 m away from the wall?
Let AB be the ladder and C is the junction of wall and ground, AB = 5 m B Let CA = meters, CB = meters According to the equation, increases, decreases and = 2 cm/s In AC2 + BC2 = AB2 [Using...
A balloon, which always remains spherical has a variables radius. Find the rate at which its volume is increasing with the radius when the later is 10 cm.
Since, V = = = Therefore, the volume is increasing at the rate of cm3/sec.
A balloon, which always remains spherical on inflation, is being inflated by pumping in 900 cubic centimeters of gas per second. Find the rate at which the radius of the balloon increases when the radius is 15 cm.
Let cm be the radius of the spherical balloon at time According to the question, Radius of balloon is increasing at the rate of cm sec.
The length of a rectangle is decreasing at the rate of 5 cm/minute. When = 8 cm and = 6 cm, find the rates of change of (a) the perimeter and (b) the area of the rectangle.
Given: Rate of decrease of length of rectangle is 5 cm/minute. is negative = –5 cm/minute Also, Rate of increase of width of rectangle is 4 cm/minute is positive = 4 cm/minute (a) Let denotes...
The radius of a circle is increasing at the rate of 0.7 cm/s. What is the rate of its circumference?
Let cm be the radius of the circle at time Rate of increase of radius of circle = 0.7 cm/sec is positive and = 0.7 cm/sec Let be the circumference of the circle. Rate of change of...
A stone is dropped into a quite lake and waves move in circles at the rate of 5 cm/sec. At the instant when radius of the circular wave is 8 cm, how fast is the enclosed area increasing?
Let cm be the radius of the circular wave at time Rate of increase of radius of circular wave = 5 cm/sec is positive and = 5 cm/sec Let be the enclosed area of the circular wave. Rate of...
An edge of a variable cube is increasing at the rate of 3 cm per second. How fast is the volume of the cube increasing when the edge if 10 cm long?
Let cm be the edge of variable cube at time Rate of increase of edge = 3 cm/sec is positive and = 3 cm/sec Let be the volume of the cube. Rate of change of volume of cube = = = = cm3/sec...
The radius of the circle is increasing uniformly at the rate of 3 cm per second. Find the rate at which the area of the circle is increasing when the radius is 10 cm.
Leave cm alone the range of the circle at time Pace of increment of span of circle = 3 cm/sec dx/dt is positive and = 3 cm/sec Let y be the space of the circle. Pace of progress of space of circle =...
The volume of a cube is increasing at the rate of 8 cm3/sec. How fast is the surface area increasing when the length of an edge is 12 cm?
Let cm be the edge of the cube. Given: Rate of increase of volume of cube = 8 cm3/sec is positive = 8 ……….(i) Let be the surface area of the cube, i.e., Rate of change of surface area of...
Find the rate of change of the area of a circle with respect to its radius when (a) = 3 cm (b) = 4 cm
et denote the area of the circle of variable radius Area of circle Rate of change of area w.r.t. = (a) When cm, then sq. cm (b) When cm, then sq. cm
In figure, if ∠BAC =90° and AD⊥BC. Then, (a) BD.CD = BC² (b) AB.AC = BC² (c) BD.CD=AD² (d) AB.AC =AD²
Solution: c) BD.CD=AD² Explanation: From triangles ADB and ADC, Now according to the question, we have, ∠ADB = ∠ADC = 90° (Since AD ⊥ BC) ∠DBA = ∠DAC [As each angle = 90°- ∠C] Using AAA criterion...