2)
x(x²-2) = x³+8
x × x² - x×-2-x³ = 8
x³-2x-x³ = 8
-2x = 8
x = -4
4)
(x+7)(x-7)-(x-3)² = 53
x×x + x×(-7) + 7×x + 7×(-7) - x² + 6x - 9 = 53
x²-7x+7x-49-x²+6x-9 = 53
x²-49-x²+6x-9=53
-49+6x-9 = 53
6x = 53+49+9
6x = 111
x = 111:6
x = 18,5
6)
(x-2)³+(x+2)³ = 2x(x²-1)+3
x³-6x²+12x-8+x³+6x²+12x+8-2x²+2x = 3
26x = 3
x = 3(дробь)26