Question

Solve equation using factorisation method:

(x + 1)(2x + 8) = (x + 7)(x + 3)

Answer 1

(x + 1)(2x + 8) = (x + 7)(x + 3)

⇒ 2x² + 8x + 2x + 8 = x² + 3x + 7x + 21

⇒ 2x² + 10x + 8 = x² + 10x + 21

⇒ x² – 13 = 0

⇒ `x^2 - (sqrt13)^2 = 0`

⇒ `(x + sqrt13)(x -sqrt13) = 0`

If `x + sqrt13 = 0` or `x - sqrt13 = 0`

⇒ `x = -sqrt13` or `x = sqrt13`