5) (2x-1)(2x+1) = 2(x-3)² + x(2x-8).

Решение: $$4x^2 - 1 = 2(x^2 - 6x + 9) + 2x^2 - 8x$$ $$4x^2 - 1 = 2x^2 - 12x + 18 + 2x^2 - 8x$$ $$4x^2 - 1 = 4x^2 - 20x + 18$$ $$-1 = -20x + 18$$ $$20x = 19$$ $$x = \frac{19}{20}$$ Ответ: 19/20.