log4(20)與log3(12)比較大小 log3(4)與log4(5)比較大小?越簡明越好!
log4(20)與log3(12)比較大小 log3(4)與log4(5)比較大小?越簡明越好!
(如果用換底公式,怎么換成同一個底啊.)
語文人氣:495 ℃時間:2020-02-05 19:26:40
優(yōu)質(zhì)解答
log4(20)=log4(5)+1,log3(12)= log3(4)+1,很明顯log3(4)與log4(5)比較大小即可.
log4(5)/log3(4)=log4(5)*log4(3)<(log4(5)+log4(3))^2/4<(2)^2/4=1
所以,log3(4)大于log4(5)
其實,a>2,loga(a+1)