Question

If the line y = 2x intersects the curve y = x² – 1 at A and B, then OA + OB and OA⋅OB is (where O is origin)

(a)  √30,5

(b)  √40, - 5

(c)  √40,4

(d)  √40,5 

Answer 1

Correct option (d)  √40,5

Let x = rcosθ, y = rsinθ. Then

r² cos2 – rsinq – 1 = 0

Now,

Therefore, r₁ and r₂ are of opposite sign.

Now,