Question

1/log(a)(b)=log(b)(a)属于什么公式（是换底公式吗?怎样证明?

Answer 1

不是换底公式

要证1/log(a)(b)=log(b)(a)

只需证 [log(b)(a)]*[log(a)(b)]=1

证明用 换底公式

[log(b)(a)]*[log(a)(b)]=lgb/lga*lga/lgb=1

所以1/log(a)(b)=log(b)(a)