(b^n)^3乘（b^2）^m-(b^3)^n乘（b^m-1）^2等于多少?
问题描述：
(b^n)^3乘（b^2）^m-(b^3)^n乘（b^m-1）^2等于多少?
答
(b^n)^3*（b^2）^m-(b^3)^n*（b^m-1）^2
=b^3n*b^2m-b^3n*b^(2m-2)
=b^(3n+2m)-b^(3n+2m-2)
=b^(3n+2m)(1-1/b^2)