Let the locus of the mid-point of the chord through the origin O of the parabola y2=4x be the curve S . Let P be any point on S . Then the locus of the point, which internally divides OP in the ratio 3:1, is :
(A)3y2=2x
(B)2y2=3x✓ Correct
(C)3x2=2y
(D)2x2=3y
Answer: (B)
Solution
A point of y2=4x is (t2,2t); the mid-point of the chord joining it to the origin is (2t2,t), whose locus S satisfies y2=2x. Let P(p,q) lie on S, so q2=2p, and let R(X,Y) divide OP internally in the ratio 3:1; then X=43p,Y=43q, i.e. p=34X,q=34Y. Substituting into q2=2p,
(34Y)2=2⋅34X⇒2Y2=3X.
The required locus is 2y2=3x.
JEE Main · 2026 · 22 Jan 2026 · Shift 2 · Single correct option