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2.8.1 对数 函数

2.8.1 对数 函数. ① ② ③. y=a x. (a>1). (0,1). Y=a x. (0<a<1). (0,1). 课前练习. 1. 复习指数函数的图象及性质 ? 2. 求下列函数的反函数 :. 2 ．解： 1 ）因为 y= 2 x ( y>0) y= 2 x 的反函数是 y=log 2 x (x>0)

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2.8.1 对数 函数

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  1. 2.8.1 对数函数

  2. ① ② ③ y=ax (a>1) (0,1) Y=ax (0<a<1) (0,1) 课前练习 1.复习指数函数的图象及性质? 2.求下列函数的反函数: 2．解：1）因为y= 2x ( y>0) y= 2x的反函数是y=log 2 x (x>0) 2）因为y=( 1/2 ) x y>0 所以x=log 1/2 y y=(1/2 )x的反函数是y=log 1/2 x (x>0) 3）因为y=a x (a>0且a=1) y>0 所以x=log a y y=ax的反函数是y=log a x 1.指数函数的图象:

  3. 一.对数函数的定义: 一般地,函数y=logax,(a>o且a=1)叫做对数函数.(0,+∞) 二.对数函数的图象和性质的应用: 练习 y x x o (1,0)

  4. 讲授新课2: 三.性质:

  5. 跟踪练习 1.求下列函数的定义域: 3.求下列函数的定义域: 5.比较下列各组数中两个数的大小:

  6. x=1 ( a>1) (1,0) 0 0 (1,0) (0< a<1) x=1 y =log x y =log x a a 课堂小结 1.正确理解对数函数的定义; 2.掌握对数函数的图象和性质; 3.能利用对数函数的性质解决有关问题. 4.搞清对数函数和指数函数的图象及性质的区别和联系: y=ax (0<a<1) (0,1) (0,1) y=ax (a>0) (0,1)

  7. 大关一中数学教研组 2006年10月 课件制作者：陈益美

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