Question

若log以18为底9的对数=a,18^b=5,则用a与b表示log以18为底45的对数/log以18为底36的对数=

Answer 1

已知log18(9)=a;log18(5)=b;

则有1=log18(18)=log18(2*9)=log18(9)+log(2)=a+log18(2);

log18(45)=log18(9*5)=log18(9)+log18(5)=a+b;

log18(36)=log18(18*2)=log18(18)+log18(2)=1+1-a;

结果为（a+b）/（2-a）