x³+y³+2xy(x+y) = (x+y)(x²-xy+y²) + 2xy(x+yx³+y³+2xy(x+y) = (x+y)(x²-xy+y²+2xyx³+y³+2xy(x+y) = (x+y)(x²+xy+y²)
x³+y³+2xy(x+y) = (x+y)(x²-xy+y²) + 2xy(x+y
x³+y³+2xy(x+y) = (x+y)(x²-xy+y²+2xy
x³+y³+2xy(x+y) = (x+y)(x²+xy+y²)