$\begin{array}{1 1}(A)\;(2,8) \\(B)\;(2,7) \\(C)\;(-2,-8) \\(D)\;(4,5) \end{array}$

Want to ask us a question? Click here

Browse Questions

Ad |

0 votes

0 votes

Any point P on the conic is $(x,x^2+7x+2)$

Its distance from $3x-y-3=0$ is

$D= \large\frac{|3x-(x^2+7x+2)-3|}{\sqrt {9+1}}$

$\qquad= \large\frac{x^2+4x+5}{\sqrt {10}}$

$\large\frac{dD}{dx}=\frac{2x+4}{\sqrt {10}}$

$\large\frac{d^2D}{dx^2}=\frac{2}{\sqrt {10}} > 0$

$\therefore$ D is least when $2x+4=0$

or $x=-2$

Required point is $(-2,-8)$

Hence D is the correct answer.

Ask Question

Tag:MathPhyChemBioOther

Take Test

x

JEE MAIN, CBSE, NEET Mobile and Tablet App

The ultimate mobile app to help you crack your examinations

...