Question

[Mei Mei]

tính:

a) \(\left(x+y+z\right)^2-\left(x+y+z\right)^2\)

b) \(\left(x-2y\right)^3-6x^2y+12xy^2+8y^3\)

Answer 1

[Nguyễn Lê Phước Thịnh]

a: \(=\left(x+y+z-x-y-z\right)\cdot A=0\cdot A=0\)

b: \(=x^3-6x^2y+12xy^2-8y^3-6x^2y+12xy^2+8y^3\)

\(=x^3-12x^2y+24xy^2\)