log25﹙3﹚=a,log25﹙4﹚=b,求log5﹙72﹚
问题描述：
log25﹙3﹚=a,log25﹙4﹚=b,求log5﹙72﹚
log1/27(1/7)=a,log1/3(1/5)=b,求log81(175)
答
∵log25﹙3﹚=log(5²)3=1/2log(5)3=a∴log(5)=2a∵log25﹙4﹚=log(5²)4=1/2log(5)4=b,∴log(5)4=2b∴log5﹙72﹚=log(5)(4×18)=log(5)4+log(5)(2×3²)=2b+1/2log(5)4+2log(5)3=2b+b+2*2a=4a+3b2log1/...