题目内容：

0.4*log以以2为底0.4的对数怎么算,具体点

优质解答

0.4*log2(0.4)
=0.4*log2(4/10)
=0.4*lg(4/10)/lg2
=0.4*(lg4-lg10)/lg2
=0.4*(lg2²/lg2-1/lg2)
=0.4*(2-1/lg2)
=0.4*(2-1/0.3010)
=-0.5788