Question

Which of the following are the roots of the quadratic equation, x² – 9x + 20 = 0 by factorisation?

Options

• 3, 4

• 4, 5

• 5, 6

• 6, 1

Answer 1

4, 5

Explanation:

Given equation is x² – 9x + 20 = 0

⇒ x² – 5x – 4x + 20 = 0

⇒ x(x – 5) – 4(x – 5) = 0

⇒ (x – 5) (x – 4) = 0

either x – 5 = 0 and x – 4 = 0

⇒ x = 5 and x = 4

∴ x = 4 and 5 are the roots of the given quadratic equation.