10) 6x(2 - 3x) - 4,5x(1 - 4x) - 6,5x + 2 = 9
12x - 18x² - 4,5x + 18x² - 6,5x + 2 = 9
x = (9 - 2) / (12 - 4,5 - 6,5)
x = 7 / 1 = 7
Ответ: x = 7