x3+y3怎样化成（x+y）（x2-xy+y2)
问题描述：
x3+y3怎样化成（x+y）（x2-xy+y2)
答
x3+y3
=x³+x²y-x²y-xy²+xy²+y³
=x²(x+y)-xy(x+y)+y²(x+y)
=(x+y)（x²-xy+y²）