對(duì)數(shù)學(xué)案2

1、〖教學(xué)目的教學(xué)目的〗了解對(duì)數(shù)的概念，了解對(duì)數(shù)運(yùn)算與指數(shù)運(yùn)算的互逆關(guān)系。掌握對(duì)數(shù)式與指數(shù)式的互化?！冀虒W(xué)重點(diǎn)教學(xué)重點(diǎn)〗對(duì)數(shù)的定義及對(duì)數(shù)式與指數(shù)式的互化?！冀虒W(xué)難點(diǎn)教學(xué)難點(diǎn)〗對(duì)數(shù)的定義的理解?！冀虒W(xué)過(guò)程教學(xué)過(guò)程〗一.導(dǎo)入新課導(dǎo)入新課1.情境：第2.2.2節(jié)例42.問(wèn)題：知道了該物質(zhì)的剩留量y，怎么求所經(jīng)過(guò)的時(shí)間x呢？二.講授新課講授新課1.對(duì)數(shù)的定義一般地，如果a(a0a1)的b次冪等于N即=N那么就稱b是?ba以a為底N的對(duì)數(shù)記作其中a叫

2、做對(duì)數(shù)的底數(shù)，N叫做bNa?log真數(shù)。2.有關(guān)對(duì)數(shù)概念的理解（1）對(duì)數(shù)式與指數(shù)式的關(guān)系（2）對(duì)數(shù)表示式的理解（3）對(duì)數(shù)的性質(zhì)①零與負(fù)數(shù)沒(méi)有對(duì)數(shù)②)10(01log???aaa③)10(1log???aaaa例４、已知求的值ma?2logna?3lognma?2例５、已知求x的值????122log212????xxx練習(xí)：課本P581，2，3，4，5，64.總結(jié)回顧總結(jié)回顧（1）對(duì)數(shù)的概念（2）對(duì)數(shù)式與指數(shù)式的互化五.板書設(shè)計(jì)板書設(shè)計(jì)