Объяснение:
1.)
5 (x + 2)^3 - 5 x^3 = 30 x^2 + 28 x
30 x^2 + 60 x + 40 = 30 x^2 + 28 x
32 x + 40 = 0
8 (4 x + 5) = 0
4 x + 5 = 0
4 x = -5
x = -5/4
