设a.b.c均为大于1的正数,且ab=10,求证:log aC+log bC>4lgC
问题描述:
设a.b.c均为大于1的正数,且ab=10,求证:log aC+log bC>4lgC
答
loga(c)+logb(c)=lgc/lga+lgc/lgb=lgc
=lgc =lgc(1/(lga*lgb) 1ga*lgb =4lgc
得证