已知log18 9=a,18^b=5,用a,b表示log(36)5

网友回答

b=log(18)5
log(36)5
=log(18)5/log(18)36
=b/[log(18)2+log(18)18]
=b/[log(18)18/9+1]
=b/[log(18)18-log(18)9+1]
=b/(2-a)
======以下答案可供参考======
供参考答案1:
log18(9)=a lg9/lg18=a 2lg3/(2lg3+lg2)=a 2lg3=2alg3+alg2 (2-2a)lg3=alg2 lg3=alg2/(2-2a) 18^b=5 log18(5)=b lg5/lg18=