Ответ: \[x^{2} + 4x - 5 = x^{2} + 4x + 4 - 9 =\] \[= (x + 2)^{2} - 9 =\] \[= (x + 2 - 3)(x + 2 + 3) =\] \[= (x - 1)(x + 5).\]