(x-y)的5次方+(y-x)的3次方=(x-y)的5次方-(x-y)的3次方=（x-y）³【（x-y）²-1】=（x-y）³（x-y+1）（x-y-1）
(x-y)^5+(y-x)^3=(x-y)^5-(x-y)^3=(x-y)^3[(x-y)^2-1]=(x-y)^3(x-y+1)(x-y-1)
