题应该是loga(a底数)c+logb(b底数)c)>=4lgc吧loga(a底数)c+logb(b底数)c)= lgc/lga + lgc/lgb = lgc(lga +lg b) / (lga*lgb)= lgc / (lga*lgb)(lga-lgb)的平方大于等于0 再在不等式左右两边同时+4lga*lgb 也就是说(l...