Verified answer

x(x² + 2x + 1) = 6(x + 1)

x(x + 1)² - 6(x + 1) = 0

(x + 1)[x(x + 1) - 6] = 0

(x + 1)(x² + x - 6) = 0

(x + 1)(x + 3)(x - 2) = 0