-8a² - 2ax - x² - (-4a² - 2ax - x²) = -8a² - 2ax - x² + 4a² + 2ax + x² = -4a²
-4a² = -4 * (-3/4)² = -4 * (9/16) = -36/16 = -9/4
-9/4 = -2.25
Ответ: -2.25