2(3a^2+2b^2)(3a^2-2b^2)
问题描述：
2(3a^2+2b^2)(3a^2-2b^2)
答
=2{(3a^2)^2-(2b^2)^2}
=2(9a^4-4b^4)
=18a^4-8b^4