Q.

If αx+βy=109 is the equation of the chord of the ellipse x29+y24=1, whose mid point is (52,12), then α+β is equal to :          [2025]

1 46  
2 58  
3 37  
4 72  

Ans.

(2)

We have, equation of ellipse as, x29+y24=1

Equation of chord with mid-point (52,12) is

xx1a2+yy1b2=x12a2+y12b2

 52(x9)+12(y4)=2536+116

 5x18+y8=109144

 40x + 18y = 109

On comparing with given equation αx+βy=109, we get

α=40 and β=18

  α+β=58.