JEE Main20252 Apr 2025Evening ShiftMathematicsParabolaActual
Let the point P of the focal chord P Q of the parabola y^2=16 x be (1,-4) . If the focus of the parabola divides the chord PQ in the ratio m : n , gcd (m, n)=1 , then m^2+n^2 is equal to :
Options
- A17
- B10
- C37
- D26
Correct answer
A. 17
Step-by-step solution
y^2=16 x ; a=4 focus S (4,0) aligned & 2 at ₁=-4 & 2(4) t ₁=-4 & t ₁=- 1 2 & t ₁ t ₂=-1 aligned aligned & t ₂=2 & Q ( at ₂^2, 2 at ₂ )=(16,16) aligned Let, S divides PQ internally in : 1 ratio aligned & 16 -4 +1 =0 & = 1 4 = m n & ~m ^2+ n ^2=1+16=17 aligned