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對(duì)數(shù)與對(duì)數(shù)運(yùn)算,引 入,例1截止到1999年底,我國(guó)人口約13億。如果今后能將人口年平均增長(zhǎng)率控制在1%,那么經(jīng)過(guò)20年后,我國(guó)人口數(shù)最多為多少(精確到億)?,知識(shí)點(diǎn)1:對(duì)數(shù)的定義,1.對(duì)數(shù)的定義,知識(shí)點(diǎn)2:常用對(duì)數(shù)的定義,我們通常將以10為底的對(duì)數(shù)叫做常用對(duì)數(shù)(common log- arithm),并把常用對(duì)數(shù)log10N簡(jiǎn)記為lgN。,知識(shí)點(diǎn)3:自然對(duì)數(shù)的定義,在科學(xué)技術(shù)中常使用以無(wú)理數(shù)e=2.718 28為底的對(duì)數(shù),以e為底的對(duì)數(shù)叫自然對(duì)數(shù),并把自然對(duì)數(shù)logeN簡(jiǎn)記作lnN。,2.對(duì)數(shù)式與指數(shù)式的互化,,練 一 練,例2將下列指數(shù)式化為對(duì)數(shù)式,對(duì)數(shù)式化為指數(shù)式:,3.對(duì)數(shù)的性質(zhì),對(duì)數(shù)式有意義的條件,例3求下列各式中x的取值范圍:,,練 一 練,例4,4.對(duì)數(shù)的運(yùn)算法則,例5,例6,配套練習(xí)題,作業(yè)布置,