7) (x + 5) (2 x² - 2) -10x²

Решение: $$(x+5)(2x^2-2) - 10x^2 = x(2x^2-2) + 5(2x^2-2) - 10x^2 = 2x^3 - 2x + 10x^2 - 10 - 10x^2 = 2x^3 + (10-10)x^2 - 2x - 10 = 2x^3 - 2x - 10$$ Ответ: $$2x^3 - 2x - 10$$