IIT-JEE 2011 · Paper 2 · Mathematics Q51

MathematicsMultiple correct+4Question 51 of 60

Let $L$ be a normal to the parabola $y^2=4x$ . If $L$ passes through the point $(9,6)$ , then $L$ is given by

y-x+3=0

y+3x-33=0

y+x-15=0

y-2x+12=0

Answer and worked solution

Official answer: A, B, D

Normal in slope form: $y=mx-2m-m^3$ . Through $(9,6)$ : $m^3-7m+6=0$ , i.e. $(m-1)(m-2)(m+3)=0$ .

Normals.

(A), (B), (D)

Topics:Tangents and normals to conics Parabola

IIT-JEE 2011 · Paper 2, Mathematics question 51