a) x3 + 64 = x3 + 43 = x3 + 43 = (x + 4) (x2 - 64x + 16)
b) (x - 2)3 + (x + 1)3 = x3 - 3.x2.2 + 3.x.22 - 23 + x3 + 3.x2.1 + 3.x.12 + 13
= x3 - 6x2 + 12x - 8 + x3 + 3x2 + 3x + 1
= x6 - 3x4 + 15x2 - 7
c)(3x + 4) (9x2 - 12x + 16) = (3x + 4) [(3x)2 - 3x.4 + 42] = 3x3 + 42