计算a^2·a^4+2a·a^5-(2a^3)^2
问题描述：
计算a^2·a^4+2a·a^5-(2a^3)^2
答
a^2·a^4+2a·a^5-(2a^3)^2
=a^6+2a^6-4a^6
=-a^6