(x² - 1)(x² + 3) = (x² + 1)² + x
x⁴ + 3x² - x² - 3 = x⁴ + 2x² + 1 + x
x⁴ + 2x² - 3 - x⁴ - 2x² - 1 - x = 0
- x - 4 = 0
- x = 4
x = - 4
- 3x(2 - x) + (3x + 1)(x - 2) = - 6x + 3x² + 3x² - 6x + x - 2 = 6x² - 11x - 2
2a² + 8ab + 8b² = 2(a² + 4ab + 4b²) = 2(a + 2b)² = 2(a + 2b)(a + 2b)