3^a=2
所以
log(3,2)=a -----就这样表示对数吧
所以
log以3为底8－2log以3为底6
=log(3,2³)-2（log(3,2)+1）
=3log(3,2)-2log(3,2)-2
=log(3,2)-2
=a-2=log(3,2³)-2（log(3,2)+1）这＋1怎么得来log以3为底6=log(3,6)=log(3,2×3)=log(3,2)+log(3,3)=log(3,2)+1