若a>0,a^(3/4)=27,则log(1/3)a=

问题描述:

若a>0,a^(3/4)=27,则log(1/3)a=

∵a^(3/4)=27
∴两边同时以1/3为底取对数
则㏒(1/3)a^(3/4)=㏒(1/3)27
∴3/4·㏒(1/3)a=㏒(1/3)27=㏒(3^-1)3^3=-3
∴㏒(1/3)a=-4