Q.

Let one end of a focal chord of the parabola y2=16x be (16,16). If P(α,β) divides this focal chord internally in the ratio 5:2, then the minimum value of α+β is equal to : [2026]

1 7  
2 5  
3 16  
4 22  

Ans.

(1)

y2=16x

 parameter of point A is t=2

Parameter of point B is t=-12

Coordinates of B is (1,-4)

Case 1:

α=5+327=377

β=-20+327=127

α+β=7

Case 2:

α=2+807,    β=-8+807

α+β=22

So minimum value of α+β=7