Question

Giúp mình giải với ạ

Answer 1

b: \(\left(a+b\right)^3-3ab\left(a+b\right)\)

\(=a^3+3a^2b+3ab^2+b^3-3a^2b-3ab^2\)

\(=a^3+b^3\)

c: \(\left(a-b\right)^3+3ab\left(a-b\right)\)

\(=a^3-3a^2b+3ab^2-b^3+3a^2b-3ab^2\)

\(=a^3-b^3\)

d: \(\left(x+y\right)^2-2xy\)

\(=x^2+2xy+y^2-2xy=x^2+y^2\)