x³ + 5x² - 5x - 25 = (x³ + 5x²) - (5x + 25) = x² (x + 5) - 5(x + 5) =
= (x + 5)(x² - 5) = (x + 5)(x - √5)(x + √5)
x³ + 5x² - 5x - 25 = (x³ + 5x²) - (5x + 25) = x² (x + 5) - 5(x + 5) =
= (x + 5)(x² - 5) = (x + 5)(x - √5)(x + √5)