计算 x的n+1次方×(x的n-1次方-x的n+1次方-x)

问题描述:

计算 x的n+1次方×(x的n-1次方-x的n+1次方-x)

x^(n+1)×[x^(n-1)-x^(n+1)-x]
=x^(2n)-x^(2n+2)-x^(n+2)