Question
Question: If the line y = mx+a meets the parabola y<sup>2</sup> = 4ax in two points whose abscissa are x<sub>1...
If the line y = mx+a meets the parabola y2 = 4ax in two points whose abscissa are x1 and x2 then x1 + x2 = 0 if
A
m = -1
B
m = 1
C
m = 2
D
m = -1/2
Answer
m = 2
Explanation
Solution
by eliminating y
(mx+a)2 = 4ax m2x2 + (2ma-4a)x+a2 =0
x1 and x2 are the roots such that x1 + x2 = 0
ie., ⇒ 2ma – 4a = 0 ⇒ m =2