1) x⁴ - 5x² + 4 = (x² - 1)(x² - 4) = (x - 1)(x + 1)(x - 2)(x + 2)
2) (x + y)² - 3(x + y) - 10 = (x + y - 5)(x + y + 2)
1) x⁴ - 5x² + 4 = (x² - 1)(x² - 4) = (x - 1)(x + 1)(x - 2)(x + 2)
2) (x + y)² - 3(x + y) - 10 = (x + y - 5)(x + y + 2)