3x³ - 7x² - 7x + 3 = 0
3(x³ + 1) - 7x(x + 1) = 0
3(x + 1)(x² - x + 1) - 7x(x + 1) = 0
(x + 1)(3x² - 3x + 3) - 7x(x + 1) = 0
(x + 1)(3x² - 3x + 3 - 7x) = 0
x + 1 = 0
3x² - 10x + 3 = 0
x = -1
D = 100 - 3•3•4 = 64 = 8²
х1 = (10 + 8)/6 = 3
х2 = (10 - 8)/6 = 1/3
Ответ: х = -1; 1/3; 3.