MHT CET2012MathematicsParabola
If 2 x+y+ =0 is normal to the parabola y²=8 x , then is
Options
- A-24
- B8
- C-16
- D24
Correct answer
A. -24
Step-by-step solution
Given, parabola, y²=8 x array lr & 2 y d y d x =8 & d y d x = 4 y array Slope of normal of parabola =- y 4 ( i ) Given, 2 x+y+ =0 is a equation of normal of the parabola y²=8 x . Slope of normal =-2 (ii) From Eqs. (i) and (ii), we get - y 4 =-2 y=8(8)²=8 x x=8 Now, putting the values of x and y in the equation of normal aligned 2(8)+8+ &=0 &=-24 aligned