Solution: Real numbers are simply the combination of rational and irrational numbers, in the number system. In general, all the arithmetic operations can be performed on these numbers and they...
8. Prove that the square of any positive integer is of the form 4q or 4q + 1 for some integer q.
Solution: Real numbers are simply the combination of rational and irrational numbers, in the number system. In general, all the arithmetic operations can be performed on these numbers and they...
7. Prove that the square of any positive integer is of the form 3m or 3m + 1 but not of the form 3m + 2.
Solution: Real numbers are simply the combination of rational and irrational numbers, in the number system. In general, all the arithmetic operations can be performed on these numbers and they...
6. Prove that square of any positive integer of the form 5q + 1 is of the same form.
Solution: Real numbers are simply the combination of rational and irrational numbers, in the number system. In general, all the arithmetic operations can be performed on these numbers and they...
5. Prove that if a positive integer is of form 6q + 5, then it is of the form 3q + 2 for some integer q, but not conversely.
Solution: Real numbers are simply the combination of rational and irrational numbers, in the number system. In general, all the arithmetic operations can be performed on these numbers and they...
4. For any positive integer n, prove that n3 – n divisible by 6.
Solution: Real numbers are simply the combination of rational and irrational numbers, in the number system. In general, all the arithmetic operations can be performed on these numbers and they...
3. Prove that the product of three consecutive positive integers is divisible by 6.
Solution: Real numbers are simply the combination of rational and irrational numbers, in the number system. In general, all the arithmetic operations can be performed on these numbers and...
2. Prove that the product of two consecutive positive integers is divisible by 2.
Solution: Real numbers are simply the combination of rational and irrational numbers, in the number system. In general, all the arithmetic operations can be performed on these numbers and they...
1. If a and b are two odd positive integers such that a > b, then prove that one of the two numbers (a+b)/2 and (a-b)/2 is odd and the other is even.
Solution: Real numbers are simply the combination of rational and irrational numbers, in the number system. In general, all the arithmetic operations can be performed on these numbers and they...
2. John and Jivani together have marbles. Both of them lost marbles each, and the product of the number of marbles they now have is . Form the quadratic equation to find how many marbles they to start with, if John had marbles.
Solution: Quadratic equations are the polynomial equations of degree $2$ in one variable of type $f(x) = ax2 + bx + c$ where a, b, c, ∈ R and a ≠ 0. Given, John and Jilani...
12. In fig.4.143, ∠A = ∠CED, prove that ΔCAB ∼ ΔCED. Also find the value of x.
Solution: “In a pair of similar triangles, the corresponding sides are proportional. When the sides are corresponding it means to go from one triangle to another you can multiply each side by the...
11. A vertical stick long casts a shadow long. At the same time, a tower casts a shadow long. Determine the height of the tower.
Solution: Given: Length of stick = $10cm$ Length of the stick’s shadow = $8cm$ Length of the tower’s shadow = $30m$ = $3000cm$ To find: The height of the tower = PQ. In ΔABC ∼ ΔPQR...
10. If Δ ABC and Δ AMP are two right triangles, right angled at B and M, respectively such that ∠MAP = ∠BAC. Prove that (i) ΔABC ∼ ΔAMP (ii) CA/ PA = BC/ MP
Solution: (i) Given: Δ ABC and Δ AMP are the two right triangles. To prove : ΔABC ∼ ΔAMP Proof : ∠AMP = ∠B = 90o ∠MAP = ∠BAC (Vertically Opposite...
9. Diagonals AC and BD of a trapezium ABCD with AB ∥ DC intersect each other at the point O. Using similarity criterion for two triangles, show that OA/ OC = OB/ OD
Solution: Given: OC is the point of intersection of AC and BD in the trapezium ABCD, with AB ∥ DC. To prove: OA/ OC = OB/ OD Proof : In ΔAOB and ΔCOD ∠AOB = ∠COD...
8. In the fig.4.142 given, if AB ⊥ BC, DC ⊥ BC, and DE ⊥ AC, prove that ΔCED ∼ ΔABC
Solution: Given: AB ⊥ BC, DC ⊥ BC, DE ⊥ AC To prove: ΔCED∼ΔABC From ΔABC and ΔCED ∠B = ∠E = 90o [given] ∠BAC = ∠ECD ...
7. In the fig.4.141 given, DE ∥ BC such that . If , find AD.
Solution: Given: DE∥BC $AE = (1/4)AC$ $AB = 6 cm$. To find: AD. In ΔADE and ΔABC ∠A = ∠A (Common) (Corresponding angles as AB||QR with PQ as the transversal) ∠ADE = ∠ABC (By AA...
6. In fig.4.140, and BD ⊥ AC. If , and , Find BC.
Solution: Given: BD ⊥ AC $AC = 5.7 cm$, $BD = 3.8 cm$ and $CD = 5.4 cm$ \[\angle ABC~=\text{ }{{90}^{o}}\] To find: BC ΔABC ∼ ΔBDC (By AA similarity) \[\angle BCA~=\angle DCA\text{ }=\text{...
5. In fig. 4.139, and BD⊥AC. If , and , find CD.
Solution: Given : $∠ABC = 90o$ and BD⊥AC $BD = 8 cm$ $AD = 4 cm$ To find: CD. ABC is a right angled triangle and BD⊥AC. (By AA similarity) ΔDBA∼ΔDCB BD/ CD = AD/ BD...
4. In a right-angled triangle with sides a and b and hypotenuse c, the altitude drawn on the hypotenuse is x. Prove that ab = cx.
Given : Consider ΔABC to be a right angle triangle having sides a, b and hypotenuse c. Let BD be the altitude drawn on the hypotenuse AC. To prove: ab = cx Prove : In ΔACB and ΔCDB...
3. In fig. 4.138 given, XY∥BC. Find the length of XY.
Solution: Given : XY∥BC $AX = 1 cm$, $XB = 3 cm$ and $BC = 6 cm$ To find: XY In ΔAXY and ΔABC ∠A = ∠A (Common) (Corresponding angles as AB||QR with PQ as the transversal) ∠AXY = ∠ABC...
8. The following data gives the information on the observed lifetimes (in hours) of electrical components:
Lifetimes (in hours):0 – 2020 – 4040 – 6060 – 8080 – 100100 – 120No. of components: 103552613829 Solution: Statistics is the discipline...
2. In fig.4.137, AB ∥ QR, find the length of PB.
Given : ΔPQR, AB ∥ QR $AB = 3 cm$, $QR = 9 cm$ and $PR = 6 cm$ To find: PB In ΔPAB and ΔPQR ∠P = ∠P (Common) (Corresponding angles as AB||QR with PQ as the transversal) ∠PAB = ∠PQR...
In fig. 4.136, ΔACB ∼ ΔAPQ. If , , and , find CA and AQ.
Solution: Given, ΔACB ∼ ΔAPQ $BC = 8 cm$, $PQ = 4 cm$, $BA = 6.5 cm$ and $AP = 2.8 cm$ To find: CA and AQ ΔACB ∼ ΔAPQ [given] BA/ AQ = CA/ AP = BC/ PQ (Corresponding Parts of Similar Triangles)...
15.
Solution: Given, \[cot\text{ }\theta \text{ }=\text{ }1/\surd 3\ldots \ldots .\text{ }\left( 1 \right)\] By definition we know that, \[cot\text{ }\theta \text{ }=\text{ }1/\text{ }tan\text{ }\theta...
14. If
show that
Solution: Given, \[cos\text{ }\theta \text{ }=\text{ }12/13\ldots \ldots \text{ }\left( 1 \right)\]definition we know that, \[cos\text{ }\theta \text{ }=\]Base side adjacent to ∠θ /...
13. If
show that
Solution: Given,\[sec\text{ }\theta \text{ }=\text{ }13/5\] We know that, \[sec\text{ }\theta \text{ }=\text{ }1/\text{ }cos\text{ }\theta \] \[\Rightarrowcos\text{ }\theta \text{ }=\text{ }1/\text{...
12. If
prove that
Solution: Given, \[tan\text{ }\theta \text{ }=\text{ }a/b\] From LHS, let’s divide the numerator and denominator by \[cos\text{ }\theta...
10. If
find the value of
Solution: Given, \[3\text{ }tan\text{ }\theta \text{ }=\text{ }4\] \[\Rightarrow tan\text{ }\theta \text{ }=\text{ }4/3\] From, let’s divide the numerator and denominator by \[cos\text{ }\theta .\]...
9. If
find the value of
Solution: Given, \[tan\text{ }\theta \text{ }=\text{ }a/b\] And, we know by definition that \[tan\text{ }\theta \text{ }=\]opposite side/ adjacent side Thus, by comparison Opposite side \[=\text{...
8. If
check whether
or not.
Solution: Given, \[3cot\text{ }A\text{ }=\text{ }4\] \[\Rightarrow cot\text{ }A\text{ }=\text{ }4/3~~\] By definition, \[tan\text{ }A\text{ }=\text{ }1/\text{ }Cot\text{ }A\text{ }=\text{ }1/\text{...
7
evaluate
\[~~~~\left( \mathbf{i} \right)~~~\left( \mathbf{1}+\mathbf{sin}\text{ }\mathbf{\theta } \right)\left( \mathbf{1}\mathbf{sin}\text{ }\mathbf{\theta } \right)/\text{ }\left(...
6. In △PQR, right-angled at Q,
and
. Find the value of
\[\mathbf{sin}\text{ }\mathbf{P},~\mathbf{sin}\text{ }\mathbf{R},\text{ }\mathbf{sec}\text{ }\mathbf{P}\text{ }\mathbf{and}\text{ }\mathbf{sec}\text{ }\mathbf{R}.\] Solution: Given: \[\vartriangle...
5. Given
, find
Solution We have, \[15cot\text{ }A\text{ }=\text{ }8\] Required to find: \[sin\text{ }A\text{ }and\text{ }sec\text{ }A\] As, \[15cot\text{ }A\text{ }=\text{ }8\] \[\Rightarrow cot\text{ }A\text{...
18. If tan θ =
, find the value of
Solution: Given, tan θ = \[12/13\] …….. \[\left( 1 \right)\] We know that by definition, tan θ = Perpendicular side opposite to ∠θ / Base side adjacent to ∠θ …… \[\left( 2 \right)\] On comparing...
(iii) In fig. 4.72, if AB ∥ CD. If
and
find x.
Figure 4.72 Solution: Given : AB∥CD. Required to find the value of x. Diagonals of a parallelogram bisect each other AO/ CO = BO/ DO \[\left( 3x\text{ }\text{ }19 \right)/\text{ }\left( x\text{...
1. (i) In fig. 4.70, if AB∥CD, find the value of x.(ii) In fig. 4.71, if AB∥CD, find the value of x.
Figure -4.70 Figure 4.71 Solution: Given: AB∥CD. Required to find the value of x. Diagonals of a parallelogram bisect each other. \[AO/\text{ }CO\text{ }=\text{ }BO/\text{ }DO\] \[\Rightarrow...
3. In fig. 4.58, Δ ABC is a triangle such that AB/AC = BD/DC,
find ∠BAD.
Solution: Given: Δ ABCsuch that AB/AC = BD/DC, \[\angle B\text{ }=\text{ }70\] o \[\angle C\text{ }=\text{ }50\] o Required to find: ∠BAD In ΔABC, \[\angle...
2. In figure 4.57, AE is the bisector of the exterior ∠CAD meeting BC produced in E. If
and
find CE.
Solution: Given: AE is the bisector of the exterior ∠CAD \[AB\text{ }=\text{ }10\text{ }cm,\] \[AC\text{ }=\text{ }6\text{ }cm,\] and \[BC\text{ }=\text{ }12\text{ }cm.\] Required to find: CE...
1. In a Δ ABC, AD is the bisector of ∠ A, meeting side BC at D. (vii) if
and
find AC. (viii) if
and
find BD and DC.
Solution: Given: Δ ABC and AD bisects ∠A, meeting side BC at D. \[AB\text{ }=\text{ }5.6\text{ }cm,\] \[BC\text{ }=\text{ }6\text{ }cm,\] and \[BD\text{ }=\text{ }3.2\text{ }cm\]....
17. If sec θ =
, find the value of
Solution: Given, sec θ = \[5/4\] We know that, sec θ = \[1/\] cos θ ⇒ cos θ = \[1/\text{ }\left( 5/4 \right)\text{ }=\text{ }4/5\text{ }\ldots \ldots \text{ }\left( 1 \right)\] By definition, cos θ...
16.
Solution: Given, tan θ = \[1/\text{ }\surd 7\text{ }\ldots ..\left( 1 \right)\] By definition, we know that tan θ = Perpendicular side opposite to ∠θ / Base side adjacent to ∠θ \[\ldots \ldots...
1. In a Δ ABC, AD is the bisector of ∠ A, meeting side BC at D. (v) if
and
find AB.(vi) if
and
find BC.
Solution: Given: Δ ABC and AD bisects ∠A, meeting side BC at D. \[~AC\text{ }=\text{ }4.2\text{ }cm\],\[~DC\text{ }=\text{ }6\text{ }cm,\] and \[BC\text{ }=\text{ }10\text{ }cm.\] Required...
9. The distribution below gives the weight of
students in a class. Find the median weight of students:
Solution: It’s seen that, the cumulative frequency just greater than n/\[2\text{ }\left( i.e.\text{ }30/\text{ }2\text{ }=\text{ }15 \right)\text{ }is\text{ }19\], belongs to class interval...
5. Calculate the median from the following data:
Solution: Here, we have \[N\text{ }=\text{ }250,\] So, \[N/2\text{ }=\text{ }250/\text{ }2\text{ }=\text{ }125\] The cumulative frequency just greater than \[N/\text{ }2\text{ }is\text{ }127\]then...
4. Calculate the median from the following data:
Solution: Here, we have \[N\text{ }=\text{ }140,\] So, \[N/2\text{ }=\text{ }140/\text{ }2\text{ }=\text{ }70\] The cumulative frequency just greater than \[N/\text{ }2\text{ }is\text{ }98\]then...
1. Following are the lives in hours of
pieces of the components of aircraft engine. Find the median:
\[\mathbf{715},\text{ }\mathbf{724},\text{ }\mathbf{725},\text{ }\mathbf{710},\text{ }\mathbf{729},\text{ }\mathbf{745},\text{ }\mathbf{694},\text{ }\mathbf{699},\text{ }\mathbf{696},\text{...
4. If
, compute
Solution: Given that, \[sin\text{ }A\text{ }=\text{ }9/41~\ldots \ldots \ldots \ldots .\text{ }\left( 1 \right)\] Required to find: \[cos\text{ }A,\text{ }tan\text{ }A\] By definition, we...
3. In fig. 5.37, find
and
. Is
Solution: By using Pythagoras theorem in \[\vartriangle PQR\], we have \[P{{R}^{2}}~=\text{ }P{{Q}^{2}}~+\text{ }Q{{R}^{2}}\] Putting the length of given side PR and PQ in the above equation...
1. In a Δ ABC, AD is the bisector of ∠ A, meeting side BC at D.(iii) if
and
find BD.(iv) if
and
find BD and DC.
Given: Δ ABC and AD bisects ∠A, meeting side BC at D. \[~AB\text{ }=\text{ }3.5\text{ }cm\], \[AC\text{ }=\text{ }4.2\text{ }cm,\] and \[DC\text{ }=\text{ }2.8\text{ }cm\]. Required...
6. Find the missing value of for the given distribution whose mean is
$x:$$5$$8$$10$$12$$p$$20$$25$$f:$$2$$5$$8$$22$$7$$4$$2$ Solution: $x$$f$$fx$$5$$2$$10$$8$$5$$40$$10$$8$$80$$12$$22$$264$$P$$7$$7p$$20$$4$$80$$25$$2$$50$$N=50$$\sum{fx=524+7p}$ We know that, Mean...
2. The following is the distribution of height of students of a certain class in a certain city:
Find the median height. Solution: Here, we have N = \[420,\] So\[,\text{ }N/2\text{ }=\text{ }420/\text{ }2\text{ }=\text{ }210\] The cumulative frequency just greater than \[N/2\text{ }is\text{...
4. If the mean of the given data is , find
$x:$$5$10$15$$20$$25$$f:$$6$$p$$6$$10$$5$ Solution: $x$$f$$fx$$5$$6$$30$$10$$p$$10p$$15$$6$$90$$20$$10$$200$$25$$5$$125$$N=p+27$$\sum{fx=445+10p}$ We know that, Mean $=\sum{fx/N=\left( 445+10p...
3. If is the mean of given data. Find the value of
$x:$$10$$15$$p$$25$$35$$f:$$3$$10$$25$$7$$5$ Solution: $x$$f$$fx$$10$$3$$30$$15$$10$$150$$p$$25$$25p$$25$$7$$175$$35$$5$$175$$N=50$$\sum{fx=530+25p}$ We know that, Mean $=\sum{fx/N=\left( 2620+25p...
14. The lengths of the diagonals of a rhombus is
Find each side of the rhombus.
Solution: Let ABCD be a rhombus and AC and BD be the diagonals of ABCD. So, AC = \[24cm\text{ }and\text{ }BD\text{ }=\text{ }10cm\] \[\] We know that diagonals of a rhombus bisect each other at...
1. In a Δ ABC, AD is the bisector of ∠ A, meeting side BC at D(i) if BD = 2.5 cm, AB = 5 cm, and AC = 4.2 cm, find DC.(ii) if BD = 2 cm, AB = 5 cm, and DC = 3 cm, find AC
Given: Δ ABC and AD bisects ∠A, meeting side BC at D. \[BD\text{ }=\text{ }2.5cm\], \[AB\text{ }=\text{ }5\text{ }cm,\] and\[AC\text{ }=\text{ }4.2\text{ }cm\]. Required to...
2. Find the mean of the given data:
$x:$$19$$21$$23$$25$$27$$29$$31$$f:$$13$$15$$16$$18$$16$$15$$13$ Solution: $x$$f$$fx$$19$$13$$247$$21$$15$$315$$23$$16$$368$$25$$18$$450$$27$$16$$432$$29$$15$$435$$31$$13$$403$$N=106$$\sum{fx}=2620$...
13. In a ∆ABC, AB = BC = CA =
and AD ⊥ BC. Prove that
(i) AD = a\[\surd \mathbf{3}\] (ii) Area (∆ABC) = \[\surd \mathbf{3}\text{ }{{\mathbf{a}}^{\mathbf{2}}}\] Solution: (i) In ∆ABD and ∆ACD, we have∠ADB = ∠ADC = \[{{90}^{o}}\]AB = AC [Given]AD =...
12. In an isosceles triangle ABC, if AB = AC =
and the altitude from A on BC is
\[\mathbf{5cm},\]find BC. Solution: Given, An isosceles triangle ABC, AB = AC = \[13cm,\text{ }AD\text{ }=\text{ }5cm\] Required to find: BC In ∆ ADB, by using Pythagoras theorem, we have...
11. ABCD is a square. F is the mid-point of AB. BE is one third of BC. If the area of ∆ FBE =
, find the length of AC.
Solution: Given, ABCD is a square. And, F is the mid-point of AB. BE is one third of BC. Area of ∆ FBE = \[108c{{m}^{2}}\] Required to find: length of AC Let’s assume the sides of the square to be...
10. A triangle has sides
Find the length to one decimal place, of the perpendicular from the opposite vertex to the side whose length is
Solution: From the fig. \[AB\text{ }=\text{ }5cm,\text{ }BC\text{ }=\text{ }12\text{ }cm\text{ }and\text{ }AC\text{ }=\text{ }13\text{ }cm.\] Then, \[A{{C}^{2}}~=\text{ }A{{B}^{2}}~+\text{...
9. Using Pythagoras theorem determine the length of AD in terms of b and c shown in Fig
Solution: We have, In ∆BAC, by Pythagoras theorem, we have \[\begin{array}{*{35}{l}} B{{C}^{2}}~=\text{ }A{{B}^{2}}~+\text{ }A{{C}^{2}} \\ \Rightarrow...
8. Two poles of height
stand on a plane ground. If the distance between their feet is
find the distance between their tops.
Solution: Comparing with the figure, it’s given that AC = \[14\text{ }m,\text{ }DC\text{ }=\text{ }12m\text{ }and\text{ }ED\text{ }=\text{ }BC\text{ }=\text{ }9\text{ }m\] Construction: Draw...
7. The foot of a ladder is
away from a wall and its top reaches a window
above the ground. If the ladder is shifted in such a way that its foot is
away from the wall, to what height does its tip reach?
Solution: Let’s assume the length of ladder to be, AD = BE = x m So, in ∆ACD, by Pythagoras theorem We have, \[\begin{array}{*{35}{l}} ...
6. In an isosceles triangle ABC, AB =
Calculate the altitude from A on BC.
Solution: Given, ∆ABC, AB = AC = \[25\text{ }cm\text{ }and\text{ }BC\text{ }=\text{ }14.\] \[\] In ∆ABD and ∆ACD, we see...
5. Two poles of heights
stand on a plane ground. If the distance between their feet is
, find the distance between their tops.
Solution: Let CD and AB be the poles of height \[11m\text{ }and\text{ }6m.\] Then, its seen that CP = \[11\text{ }\text{ }6\text{ }=\text{ }5m.\] From the figure, AP should be \[12m\] (given) In...
4. A ladder
long reaches a window of a building
above the ground. Find the distance of the foot of the ladder from the building.
Solution: In ∆ABC, by Pythagoras theorem \[\begin{array}{*{35}{l}} A{{B}^{2}}~+\text{ }B{{C}^{2}}~=\text{ }A{{C}^{2}} \\ \Rightarrow {{15}^{2}}~+\text{...
3. A man goes
due west and then
due north. How far is he from the starting point?
Solution:  ...
2. The sides of certain triangles are given below. Determine which of them are right triangles.
\[\begin{array}{*{35}{l}} \left( \mathbf{i} \right)\text{ }\mathbf{a}\text{ }=\text{ }\mathbf{7}\text{ }\mathbf{cm},\text{ }\mathbf{b}\text{ }=\text{ }\mathbf{24}\text{...
1. If the sides of a triangle are
long, determine whether the triangle is a right-angled triangle.
Solution: We have, Sides of triangle as \[\begin{array}{*{35}{l}} AB\text{ }=\text{ }3\text{ }cm \\ BC\text{ }=\text{ }4\text{ }cm \\ AC\text{...
1. Calculate the mean for the given distribution:
$x:$$5$$6$$7$$8$$9$$f:$$4$$8$$14$$11$$3$ Solution: $x$$f$$fx$$5$$4$$20$$6$$8$$48$$7$$14$$98$$8$$11$$88$$9$$3$$27$$N=40$$\sum{fx=281}$ Mean $=\sum{fx/n=281/40}$ $\therefore $ Mean...
1. Fill in the blanks using the correct word given in brackets:
(i) All circles are ____________ (congruent, similar). (ii) All squares are ___________ (similar, congruent). (iii) All ____________ triangles are similar (isosceles, equilaterals). (iv) Two...
12. The car hire charges in a city comprise of a fixed charges together with the charge for the distance covered. For a journey of 12 km, the charge paid is ₹ 89 and for a journey of 20 km, the charge paid is ₹ 145. What will a person have to pay for travelling a distance of 30 km?
Solution: Let the fixed charge of the car be ₹ x and, Let the variable charges of the car be ₹ y per km. So according to the question, we get \[2\] equations \[x\text{ }+\text{ }12y\text{ }=\text{...
11. In a ΔABC, ∠A = xo, ∠B = 3xo, ∠C = yo. If 3y – 5x = 30, prove that the triangle is right angled.
Solution: We need to prove that ΔABC is right angled. \[\angle A\text{ }=\text{ }{{x}^{o}},\angle B\text{ }=\text{ }3{{x}^{o}}\]and \[\angle C\text{ }=\text{ }{{y}^{o}}\] Sum of the three angles in...
10. Yash scored 40 marks in a test, getting 3 marks for each right answer and losing 1 mark for each wrong answer. Had 4 marks been awarded for each correct answer and 2 marks been deducted for each incorrect answer, then Yash would have scored 50 marks. How many questions were there in the test?
Solution: Let the total number of correct answers be x and the total number of incorrect answers be y. Their sum will give the total number of questions in the test = x + y According to the question...
9. In a cyclic quadrilateral ABCD, ∠A = (2x + 4)o, ∠B = (y + 3)o, ∠C = (2y + 10)o, ∠D = (4x – 5)o. Find the four angles.
Solution: The sum of the opposite angles of cyclic quadrilateral should be 180o. And, in the cyclic quadrilateral ABCD, Angles \[\angle A\] and \[\angle C\] & angles \[\angle B\] and \[\angle...
8. In a ΔABC, ∠A = xo, ∠B = (3x – 2)o, ∠C = yo. Also, ∠C – ∠B = 90. Find the three angles.
Solution: Given, \[\angle A\text{ }=\text{ }{{x}^{o}}\] \[\angle B\text{ }=\text{ }{{\left( 3x\text{ }\text{ }2 \right)}^{o}},\] \[\angle C\text{ }=\text{ }{{y}^{o}}\]Also given, \[\angle C\text{...
7. 2 men and 7 boys can do a piece of work in 4 days. The same work is done in 3 days by 4 men and 4 boys. How long would it take one man and one boy to do it?
Solution: Let the time required for a man alone to finish the work be x days The time required for a boy alone to finish the work be y days. Then, The work done by a man in one day \[=\text{ }1/x\]...
5. A and B each has some money. If A gives ₹ 30 to B, then B will have twice the money left with A. But, if B gives ₹ 10 to A, then A will have thrice as much as is left with B. How much money does each have?
Solution: Let he money with A be ₹ x and the money with B be ₹ y. According to the question, Case 1: If A gives ₹ \[30\]to B, then B will have twice the money left with A. Equation, \[y\text{...
The income of X and Y are in the ratio of 8: 7 and their expenditures are in the ratio 19: 16. If each saves ₹ 1250, find their incomes.
Solution: Leave the pay alone signified by x and the consumption be meant by y. Then, at that point, from the inquiry we have The pay of X is ₹ 8x and the use of X is 19y. The pay of Y is ₹ 7x and...
3. In a rectangle, if the length is increased by 3 metres and breadth is decreased by 4 metres, the area of the triangle is reduced by 67 square metres. If length is reduced by 1 metre and breadth is increased by 4 metres, the area is increased by 89 sq. metres. Find the dimension of the rectangle.
Solution: Let the length and breadth of the rectangle be x units and y units. The area of rectangle = xy sq.units Length is increased by 3 m ⇒ The new length is \[x+3\] Breadth is reduced by 4 m...
2. The area of a rectangle remains the same if the length is increased by 7 metres and the breadth is decreased by 3 metres. The area remains unaffected if the length is decreased by 7 metres and the breadth is increased by 5 metres. Find the dimensions of the rectangle.
Solution: Let the length and breadth of the rectangle be x units and y units respectively. Hence, the area of rectangle = xy sq.units Length is increased by 7 m ⇒ now, the new length is...
If in a rectangle, the length is increased and breadth reduced each by 2 units, the area is reduced by 28 square units. If, however the length is reduced by 1unit and the breadth increased by 2units, the area increases by 33square units. Find the area of the rectangle.
Solution: Let the length and breadth of the rectangle be x units and y units respectively. The area of rectangle = xy sq.units Case 1: Length is increased by 2 units ⇒ The new length is \[x+2\]units...
12. Show that the square of any positive integer cannot be of the form 6m + 2 or 6m + 5 for any integer m.
Solution: Let the positive integer = a According to Euclid’s division algorithm, a = 6q + r, where 0 ≤ r < 6 \[{{a}^{2}}={{\left( 6q+r \right)}^{2}}=36{{q}^{2}}+{{r}^{2}}+12qr\],\[\because...
11. Show that any positive odd integer is of the form 6q +1 or 6q + 3 or 6q + 5, where q is some integer.
Let ‘a’ be any positive integer. Then from Euclid’s division lemma, a = bq+r; where 0 < r < b Putting b=6 we get, ⇒ a = 6q + r, 0 < r < 6 For r = 0, we get\[a=6q=2\left( 3q...
9. Prove that the square of any positive integer is of the form 5q or 5q + 1, 5q + 4 for some integer q.
Solution: Let ‘a’ be any positive integer. Then, According to Euclid’s division lemma, a=bq+r According to the question, when b = 5. \[a=5k+r,n<r<5\] When r = 0, we get, a = 5k ...
8. Prove that the square of any positive integer is of the form 4q or 4q + 1 for some integer q.
Let ‘a’ be any positive integer. Then, According to Euclid’s division lemma, a=bq+r According to the question, when b = 4. \[a=4k+r,n<r<4\] When r=0, we get a=4k \[\to...
5. Prove that if a positive integer is of form 6q + 5, then it is of the form 3q + 2 for some integer q, but not conversely.
Let n= 6q+5 be a positive integer for some integer q. An integer is positive if it is greater than zero. We know that any positive integer can be of the form 3k, or 3k+1, or 3k+2. ∴ q can be 3k or,...
4. Can two numbers have
as their HCF and
as theirLCM? Give reason.
Solution: On dividing \[380\]by \[16\]we get,\[23\]as the quotient and\[12\]as the remainder. Now, since the LCM is not exactly divisible by the HCF its can be said that two numbers cannot have...
2. Find the LCM and HCF of the following integers by applying the prime factorization method:(v)
(vi]
Solution: First, Find the prime factors of the given integers: \[84,\text{ }90\text{ }and\text{ }120\] For, \[\begin{array}{*{35}{l}} ~84\text{...
2. Find the LCM and HCF of the following integers by applying the prime factorization method:(iii)
(iv)
Solution: First, find the prime factors of the given integers: 8, 9 and 25 For, \[8\text{ }=\text{ }2\text{ }\times...
4. For any positive integer n, prove that n3 – n divisible by 6.
Let, n be any positive integer. And since any positive integer can be of the form 6q, or 6q+1, or 6q+2, or 6q+3, or 6q+4, or 6q+5. (From Euclid’s division lemma for b= 6) We have n3 – n =...
2. Find the LCM and HCF of the following integers by applying the prime factorization method:
(i) 12, 15 and 21(ii) \[\mathbf{17},\text{ }\mathbf{23}\text{ }\mathbf{and}\text{ }\mathbf{29}\] Solution: First, find the prime factors of the given integers: \[12,\text{ }15\text{ }and\text{...
1. Find the LCM and HCF of the following pairs of integers and verify that LCM × HCF = Product of the integers:
(i) \[\mathbf{26}\text{ and }\mathbf{91}\](ii) \[\mathbf{510}\text{ and }\mathbf{92}\] Solution: Given integers are\[\mathbf{26}\text{ and...
11. Prove that for any prime positive integer
is an irrational number.
Solution: Consider \[\surd p\] as a rational number Assume\[\surd p\text{ }=\text{ }a/b\] where a and b are integers and \[b\text{ }\ne \text{ }0\] By squaring on both sides \[p\text{ }=\text{...
10. Prove that √2 + √3 is irrational.
Solution: Let’s assume on the contrary that \[\surd 2\text{ }+\text{ }\surd 3\]is a rational number. Then, there exist co prime positive integers a and b such that \[\surd 2\text{ }+\text{ }\surd...
9. Prove that
is irrational.
Solution: Let’s assume on the contrary that \[\surd 5\text{ }+\text{ }\surd 3\] is a rational number. Then, there exist co prime positive integers a and b such that\[\surd 5\text{ }+\text{ }\surd...
8. Prove that
is an irrational number.
Solution: Let’s assume on the contrary that \[2\text{ }\text{ }3\surd 5\]is a rational number. Then, there exist co prime positive integers a and b such that \[2\text{ }\text{ }3\surd 5\text{...
7. Prove that
is an irrational number.
Solution: Let’s assume on the contrary that \[2\surd 3\text{ }\text{ }1\] is a rational number. Then, there exist co prime positive integers a and b such that \[2\surd 3\text{ }\text{ }1\text{...
6. Show that
is an irrational number.
Solution: Let’s assume on the contrary that \[5\text{ }\text{ }2\surd 3\] is a rational number. Then, there exist co prime positive integers a and b such that \[5\text{ }\text{ }2\surd 3\text{...
5. Prove that
is an irrational number.
Solution: Let’s assume on the contrary that \[4\text{ }\text{ }5\surd 2\] is a rational number. Then, there exist co prime positive integers a and b such that \[4\text{ }\text{ }5\surd 2\text{...
4. Show that
is an irrational number
Solution: Let’s assume on the contrary that \[3\text{ }+\text{ }\surd 2\] is a rational number. Then, there exist co prime positive integers a and b such that \[3\text{ }+\text{ }\surd 2=\text{...
3. Show that
is an irrational number.
Solution: Let’s assume on the contrary that \[2\text{ }\text{ }\surd 3\] is a rational number. Then, there exist co prime positive integers a and b such that\[2\text{ }\text{ }\surd 3=\text{ }a/b\]...
3. Prove that the product of three consecutive positive integers is divisible by 6.
Let n be any positive integer. Thus, the three consecutive positive integers are n, n+1 and n+2. We know that any positive integer can be of the form 6q, or...
2. Prove that the following numbers are irrationals.(iii)
(iv)
Solution: Let’s assume on the contrary that \[4\text{ }+\text{ }\surd 2\] is a rational number. Then, there exist co prime positive integers a and b such that \[4\text{ }+\text{ }\surd 2\text{...
Solve each of the following systems of equations by the method of cross-multiplication:
\[\mathbf{13}.\]\[~\mathbf{x}/\mathbf{a}\text{ }+\text{ }\mathbf{y}/\mathbf{b}\text{ }=\text{ }\mathbf{a}\text{ }+\text{ }\mathbf{b}\] \[\mathbf{x}/{{\mathbf{a}}^{\mathbf{2}~}}+\text{...
Solve each of the following systems of equations by the method of cross-multiplication:
57/(x + y) + 6/(x – y) = 5 38/(x + y) + 21/(x – y) = 9 Solution: Let substitute $\frac{1}{\left( x+y \right)}=u$ and $\frac{1}{\left( x-y \right)}=v$, \[57u\text{ }+\text{ }6v\text{ }=\text{ }5\]...
Solve each of the following systems of equations by the method of cross-multiplication:
\[\mathbf{9}.\] \[\mathbf{5}/\left( \mathbf{x}\text{ }+\text{ }\mathbf{y} \right)\text{ }\text{ }\mathbf{2}/\left( \mathbf{x}\text{ }-\mathbf{y} \right)\text{ }=\text{ }-\mathbf{1}\]...
Solve each of the following systems of equations by the method of cross-multiplication:
\[\mathbf{7}.\]\[~\mathbf{x}\text{ }+\text{ }\mathbf{ay}\text{ }=\text{ }\mathbf{b}\] \[\mathbf{ax}\text{ }+\text{ }\mathbf{by}\text{ }=\text{ }\mathbf{c}\] \[\mathbf{8}.\] \[\mathbf{ax}\text{...
Solve each of the following systems of equations by the method of cross-multiplication:
\[\mathbf{5}.\] \[\left( \mathbf{x}\text{ }+\text{ }\mathbf{y} \right)/\text{ }\mathbf{xy}\text{ }=\text{ }\mathbf{2}\] \[\left( \mathbf{x}\text{ }\text{ }\mathbf{y} \right)/\text{...
Solve each of the following systems of equations by the method of cross-multiplication:
2x + y = 35, 3x + 4y = 65 Solution: Given \[\mathbf{2x}\text{ }+\text{ }\mathbf{y}\text{ }\text{ }-\mathbf{35}\text{ }=\text{ }\mathbf{0}\] \[\mathbf{3x}\text{ }+\text{ }\mathbf{4y}\text{ }\text{...
2. Prove that the following numbers are irrationals.
(i) \[\mathbf{2}/\surd \mathbf{7}\] ii) \[\mathbf{3}/\left( \mathbf{2}\surd \mathbf{5} \right)\] Solution: Let’s assume on the contrary that \[2/\surd 7\] is a rational number. Then, there exist...
Solve each of the following systems of equations by the method of cross-multiplication:
\[\mathbf{x}\text{ }+\text{ }\mathbf{2y}\text{ }+\text{ }\mathbf{1}\text{ }=\text{ }\mathbf{0}\] \[\mathbf{2x}\text{ }\text{ }\mathbf{3y}\text{ }\text{ }\mathbf{12}\text{ }=\text{...
1. Show that the following numbers are irrational.(iii)
Solution: Let’s assume on the contrary that \[6+\surd 2\] is a rational number. Then, there exist co prime positive integers a and b such that \[6\text{ }+\text{ }\surd 2\text{ }=\text{ }a/b\]...
1. Show that the following numbers are irrational.(i)
(ii)
Solution: Consider \[1/\surd 2\] is a rational number Let us assume \[1/\surd 2\] = r where r is a rational number On further calculation we get \[1/r\text{ }=\text{ }\surd 2\] Since r is a rational...