a) (a+2)3=a3+3·a2·2+3·a·4+8=a3+6a2+12a+8
b) (2a+1)3=(2a)3+3·(2a)2·1+3·2a·12+13=
=8a3+3·4a2·1+3·2a·1+1=8a3+12a2+6a+1
c) (2x–1)3=(2x)3+3·(2x)2·(–1)+3·2x·(–1)2+(–1)3=
=8x3+3·4x2·(–1)+3·2x·1–1=8x3–12x2+6x–1
d) (x2y–x6y2)3=(x2y)3+3·(x2y)2·(–x6y2)+3·(x2y)·(–x6y2)2+(–x6y2)3=
=x6y3+3·x4y2·(–x6y2)+3·(x2y)·x12y4–x18y6=x6y3–3x10y4+3x14y5–x18y6
e) (x2n+1y4–2xn+1ym)3=
=(x2n+1y4)3+3·(x2n+1y4)2·(–2xn+1ym)+3·x2n+1y4·(–2xn+1ym)2+(–2xn+1ym)3=
=x6n+3y12+3·x4n+2y8·(–2xn+1ym)+3·x2n+1y4·4x2n+2y2m–8x3n+3y3m=
=x6n+3y12–6x5n+3ym+8+12x4n+3y2m+4–8x3n+3y3m