lg2(lg5-lg2)-lg5(lg5+3lg2)等于

分类: 作业答案 • 2021-12-19 14:55:15

问题描述：

答

lg2(lg5-lg2)-lg5(lg5+3lg2)
=lg2lg5-(lg2)^2-(lg5)^2-3lg5lg2
=-[(lg2)^2+2lg2lg5+(lg5)^2]
=-(lg2+lg5)^2
=-[lg(2*5)]^2
=-1