(x-y)的四次方+x(x+y)的三次方-y(y-x）的三次方大神们帮帮忙
问题描述：
(x-y)的四次方+x(x+y)的三次方-y(y-x）的三次方大神们帮帮忙
答
(x-y)^4+x(x+y)^3-y(y-x)^3 =(x-y)^4+x(x+y)^3+y(x-y)^3 =(x-y)^3(x-y+y)+x(x+y)^3 =x(x-y)^3+x(x+y)^3 =x[(x-y)^3+(x+y)^2] =x(x^3-3x^2y+3xy^2-y^2+x^3+3x^2y+3xy^2+y^3) =x(2x^3+6xy^2) =2x^4+6xy^3