（-x）³·x^2n-1+x^2n·（-x）²
问题描述：
（-x）³·x^2n-1+x^2n·（-x）²
答
（-x）³·x^2n-1+x^2n·（-x）²
=-x^3*x^2n-1+x^2n*x^2
=-x^3+2n-1+x^2n+2
=-x^2n+2+x^2n+2
=0