(3x²）³-7x³[x³-x（4x²+1）]
问题描述：
(3x²）³-7x³[x³-x（4x²+1）]
答
(3x²）³-7x³[x³-x（4x²+1）\
=27x^6-7x^6+28x^6+7x^4
=48x^6+7x^4