If 1 is a root of the quadratic equation and the quadratic equation has equal roots, find the value of b.

Question

Philoid · Accepted Answer

For a quadratic equation, ax² + bx + c = 0,

D = b² – 4ac

If D = 0, roots are equal

Given, 1 is a root of the quadratic equation

⇒ 3 + a – 2 = 0

⇒ a = -1

Now, the quadratic equation has equal roots

⇒ x² + 6x + b = 0 has equal roots

⇒ D = 36 – 4b = 0

⇒ b = 9