设x＝a^m,a＝b^n,则x＝(b^n)^m＝b^(mn)……………………①对①取以a为底的对数,有：log(a,x)＝m……………………………②对①取以b为底的对数,有：log(b,x)＝mn……………………………③③/②,得：log(b,x)/log(a,x)...