1、對(duì)數(shù),對(duì)數(shù)的概念與運(yùn)算,對(duì)數(shù)函數(shù),1. 對(duì)數(shù)的概念,如果a(a0,a1)的b次冪等于N,即ab=N,那么就稱b是以a為底N的對(duì)數(shù),記作logaN=b.其中,a叫做對(duì)數(shù)的底數(shù),N叫做真數(shù),N0. lgN叫常用對(duì)數(shù), lnN叫自然對(duì)數(shù),2. 對(duì)數(shù)恒等式,3. 對(duì)數(shù)的運(yùn)算性質(zhì),4. 換底公式,對(duì)數(shù),對(duì)數(shù)的概念與運(yùn)算,對(duì)數(shù)函數(shù),1. 對(duì)數(shù)的概念,2. 對(duì)數(shù)恒等式, loga1=0 logaa=1 (其中a0,a1) a =N,3. 對(duì)數(shù)的運(yùn)算性質(zhì),4. 換底公式,對(duì)數(shù),對(duì)數(shù)的概念與運(yùn)算,對(duì)數(shù)函數(shù),1. 對(duì)數(shù)的概念,2. 對(duì)數(shù)恒等式,3. 對(duì)數(shù)的運(yùn)算性質(zhì),4. 換底公式, loga(MN)=logaM+

2、logaN loga =logaM-logaN loga =nlogaM 其中a0,a1,M0,N0,nR,對(duì)數(shù),對(duì)數(shù)的概念與運(yùn)算,對(duì)數(shù)函數(shù),1. 對(duì)數(shù)的概念,2. 對(duì)數(shù)恒等式,3. 對(duì)數(shù)的運(yùn)算性質(zhì),4. 換底公式,對(duì)數(shù),對(duì)數(shù)的概念與運(yùn)算,對(duì)數(shù)函數(shù),1. 對(duì)數(shù)的概念,2. 對(duì)數(shù)恒等式,3. 對(duì)數(shù)的運(yùn)算性質(zhì),4. 換底公式,對(duì)數(shù)函數(shù)的概念 2. 對(duì)數(shù)函數(shù)的圖象和性質(zhì),對(duì)數(shù),對(duì)數(shù)的概念與運(yùn)算,對(duì)數(shù)函數(shù),1. 對(duì)數(shù)的概念,2. 對(duì)數(shù)恒等式,3. 對(duì)數(shù)的運(yùn)算性質(zhì),4. 換底公式,1. 對(duì)數(shù)函數(shù)的概念,2. 對(duì)數(shù)函數(shù)的圖象和性質(zhì),函數(shù)y=logax(a0,a1)叫做對(duì)數(shù)函數(shù),它的定義域?yàn)?0,+),(0

3、,+),R,(1,0),單調(diào)增函數(shù),單調(diào)減函數(shù),夯實(shí)基礎(chǔ)一,二、常見(jiàn)對(duì)數(shù)求值,log31= , log2 = , log327= , lg1000= , lne2= , 2 = , log2 = , = , lg2+lg5= , log256-log27= , = .,0,-1,3,3,2,3,2,1,3,3-2=x,(1) 21-x=5,求x (2) log5log3(log2x)=0,求log16x (3) 已知lg2=a,lg3=b,試用a,b表示 log512,應(yīng)用與延伸,夯實(shí)基礎(chǔ)二,夯實(shí)基礎(chǔ)二,abc,三、解不等式 (1) 33-x6 (2) lg(x-1)1,四、圖象的變換 已知f(x)=lgx的圖象,畫出下列函數(shù)的圖象,并指出與y=f(x)之間的關(guān)系. (1) y=f(-x) (2) y=-f(x) (3) y=f(x+1) (4)y=f(x)-2 (5) y=f(x)