Find the image of the point (2, -1, 5) in the line
Find the image of the point (2, -1, 5) in the line

Find the image of the point (2,-1,5) in the line

r=(11i^2j^8k^)+λ(10i^4j^11k^)
\overrightarrow{\mathrm{r}}=(11 \hat{i}-2 \hat{j}-8 \hat{\mathrm{k}})+\lambda(10 \hat{i}-4 \hat{j}-11 \hat{k})

Answer
Given: Point (2,-1,5)
Equation of line =(11 \hat{\mathrm{a}}-2 \hat{\imath}-$ \hat{k})+k(10 \hat{\imath}-4 \hat{\jmath}-11 \hat{k})
The equation of line can be re-arranged as \frac{\mathrm{x}-11}{10}=\frac{\mathrm{x}+2}{-4}=\frac{\mathrm{x}+8}{-11}=\mathrm{r}
The general point on this line is

(10r+11,4r2,11r8)
(10 r+11,-4 r-2,-11 r-8)

Let N be the foot of the perpendicular drawn from the point P(2,1,-5) on the given line. Then, this point is N(10 r+11,-4 r-2,-11 r-8) for some fixed value of r.
D.r.’s of PN are (10 r+9,-4 r-3,-11 r-3)
D.r.’s of the given line is 10,-4,-11 .
Since, PN is perpendicular to the given line, we have,

10(10r+9)4(4r3)11(11r3)=0
10(10 r+9)-4(-4 r-3)-11(-11 r-3)=0
100r+90+16r+12+121r+33=0237r=135r=135237
\begin{array}{l}
100 r+90+16 r+12+121 r+33=0 \\
237 r=135 \\
r=\frac{135}{237}
\end{array}

Then, the image of the point is

α111.1=0,β+2I¯=1,γ+89=1
\frac{\alpha-11}{-1.1}=0, \frac{\beta+2}{\bar{I}}=1, \frac{\gamma+8}{9}=1

Therefore, the image is (0,5,1).