高中必修1第二章基本初等函數(shù)(Ⅰ)§2對(duì)數(shù)函數(shù)及其性質(zhì)教學(xué)設(shè)計(jì)

1、對(duì)數(shù)函數(shù)的圖像及其性質(zhì)教學(xué)設(shè)計(jì)廣安二中 劉慧教學(xué)目標(biāo)1使學(xué)生掌握對(duì)數(shù)函數(shù)的定義，會(huì)畫(huà)對(duì)數(shù)函數(shù)的圖象，掌握對(duì)數(shù)函數(shù)的性質(zhì)2通過(guò)對(duì)數(shù)函數(shù)與指數(shù)函數(shù)互為反函數(shù)的教學(xué)，學(xué)生進(jìn)一步加深對(duì)反函數(shù)概念及函數(shù)和反函數(shù)圖象間的關(guān)系的認(rèn)識(shí)與理解3通過(guò)比較、對(duì)照的方法，學(xué)生更好地掌握兩個(gè)函數(shù)的定義、圖象及性質(zhì)，認(rèn)識(shí)兩個(gè)函數(shù)的內(nèi)在聯(lián)系，提高學(xué)生對(duì)函數(shù)思想方法的認(rèn)識(shí)和應(yīng)用意識(shí)教學(xué)重點(diǎn)與難點(diǎn) 教學(xué)重點(diǎn)是對(duì)數(shù)函數(shù)的定義、圖象及性質(zhì)難點(diǎn)是由對(duì)數(shù)函數(shù)與指數(shù)函數(shù)互為反函數(shù)這一關(guān)系，利用指數(shù)函數(shù)圖象及性質(zhì)得到對(duì)數(shù)函數(shù)的圖象及性質(zhì)教學(xué)過(guò)程一 復(fù)習(xí)引入1 什么叫對(duì)數(shù)？ 2 什么是指數(shù)函數(shù)？它有哪些性質(zhì)？問(wèn)題1：對(duì)于指數(shù)函數(shù)y=2x(x

2、R)，y是x的函數(shù)，那x是y的函數(shù)嗎？對(duì)數(shù)函數(shù)的概念：?jiǎn)栴}2：對(duì)數(shù)函數(shù)有哪些結(jié)構(gòu)特征？例1:下列函數(shù)中,哪些是對(duì)數(shù)函數(shù)?(1) y=log3(x+2) (2)y=log2x-1(3) y=logx2 (4) y=loga+1x(a-1且a0) (5) y=log3x2 (6) y=2log3xy-1xOy=log0.5x168421xy=log2x168421x二、對(duì)數(shù)函數(shù)的圖像：列表描點(diǎn)連線問(wèn)題3：選取底數(shù)a (a0, 且a1)的若干不同的值,在同一平面直角坐標(biāo)系內(nèi)作出相應(yīng)的對(duì)數(shù)函數(shù)的圖象,觀察圖象你能發(fā)現(xiàn)它們有哪些共同特征嗎?三、對(duì)數(shù)函數(shù)的性質(zhì)a10a1圖像xyOxyO性質(zhì)定義域： 值域： 過(guò)定點(diǎn)： x(0, 1)時(shí), y 0;x(1, +)時(shí), y 0.x(0, 1)時(shí), y0;x(1, +)時(shí), y0.在(0,+)上是 函數(shù)在(0,+)上是 函數(shù)奇偶性：求下列函數(shù)的定義域(a0, 且a1)例3.比較下列各組數(shù)中兩個(gè)值的大小:(1)log23.4 , log28.5 (2) log0.31.8 , log0.32.7loga5.1 , loga5.9 (