Question

If the equation qx² + px – r = 0 (q ≠ 0) has real and equal roots, then which of the following is true?

Options

• p² = qr

• p² = – 4qr

• q² = 4pr

• q² = – 4pr

Answer 1

p² = – 4qr

Explanation:

For a quadratic ax² + bx + c = 0 having equal real roots, the discriminant b² – 4ac = 0.

Here a = q, b = p, c = –r

So, p² – 4 × q × (–r) = 0 

⇒ p² + 4qr = 0

⇒ p² = – 4qr