计算[log9(5)+log3(5)]乘[log25(3)+log125(9)]
问题描述：
计算[log9(5)+log3(5)]乘[log25(3)+log125(9)]
答
换底公式
=(lg5/lg9+lg5/lg3)(lg3/lg25+lg9/lg125)
=(lg5/2lg3+lg5/lg3)(lg3/2lg5+2lg3/3lg5)
=(1/2+1)*lg5/lg3*(1/2+2/3)*(lg3/lg5
约分
=(3/2)(7/6)
=7/4