x3+y3+z3-3xyz

1、x^3+y^3+z^3-3xyz = (x^3+3yx^2+3xy^2+y^3)+z^3-3xyz-3yx^2-3xy^2 = (x+y)^3+z^3-3xy(x+y+z) = (x+y+z)[(x+y)^2-(x+y)z+z^2]-3xy(x+y+z) = (x+y+z)[(x^2+2xy+y^2-xz-yz+z^2)-2xy] = (x+y+z)(x^2+y^2+z^2-xy-yz-zx...