(x-y)的平方×（x-y）的三次方-（x-y）的四次方×（y-x）解：原式=(x-y)^2(x-y)^3-(x-y)^4(y-x)=(x-y)^(3+2)+(x-y)^(4+1)=(x-y)^5+(x-y)^5=2(x-y)^5
