来自钱贞国的问题
计算(3a^2+2/1b)(3a^2-2/1b)(9a^4+4/1b^2)
计算(3a^2+2/1b)(3a^2-2/1b)(9a^4+4/1b^2)
3回答
2020-02-11 01:51
计算(3a^2+2/1b)(3a^2-2/1b)(9a^4+4/1b^2)
计算(3a^2+2/1b)(3a^2-2/1b)(9a^4+4/1b^2)
解析
平方差公式
(前两个相乘)
(9a^4-4/1b²)(9a^4+4/1b²)
=81a^16-16/1b^4
(-2/1a-b)(2/1a-b)
=-(2/1a+b)(2/1a-b)=-(4/1a²-b²)=-4/1a²+b²