Phân tích đa thức thành nhân tử?
[tex](x+y+z)^3-x^3-y^3-z^3\\=(x+y+z)^3-(x^3+y^3+z^3)\\=(x+y+z)^3-\left [ (x+y)^3-3xy(x+y) \right+z^3 ]\\=(x+y+z)^3-\left [ (x+y+z)^3-3z(x+y)(x+y+z)-3xy(x+y) \right ]\\=(x+y+z)^3-(x+y+z)^3+3z(x+y)(x+y+z)+3xy(x+y)\\=3(x+y)\left [ z(x+y+z)+xy \right ]\\=3(x+y)(xz+yz+z^2+xy)[/tex]