lga+lgb=2,lga•lgb=1／2,则|lga／b|的值为?
问题描述：
lga+lgb=2,lga•lgb=1／2,则|lga／b|的值为?
答
lga/b=lga-lgb ,lga+lgb=2,(lga)^2+2lga*lgb+(lgb)^2=4 (lga)^2-2lga*lgb+(lgb)^2=4-4lga*lgb=2 即 (lga-lgb)^2=2 lga/b=√2