对数的性质:log10,log1aaa1
指数式和对数式的互化:logbaaNNb(0,1,0)aaN4
积、商、幂的对数:log()loglog(0,1,0,0)aaaMNMNaaMNlogloglog(0,1,0,0)aaaMMNaaMNNloglog(0,1,0)baaMbMaaM5
换底公式:loglog(0,1,0,1,0)logcacbbaaccba3
对数恒等式:logabablogbaabL/O/G/O扬中中等专业学校何萍对数的运算计算:31lg9lg81lg502211lg27lg16lg93432213432312lg10lg9lg81lg50=1lg27lg16lg9lg10lg9lg9lg50lg10lg3lg2lg91098155lglglg()lg950581811
10555lglglglg329818181解:原式化为同底且系数为1的对数积、商、幂的对数运算lg2lg50lg2lg20lg8计算:3lg2lg(510)lg2lg(210)lg2lg2(lg51)lg2(lg21)3lg2lg2lg5lg2lg2lg2lg23lg2lg2lg5lg2lg2lg2lg2(lg5lg2)lg2lg2lg10lg2lg2lg20
解:原式、
lglglgababab是两根之积的两个实根,则
lglgab——若、是方程2301000xxab、2loga2logb2320xxab设、是方程的两个根,求的值.222logloglog3abab--方程的两个根分别是1、2解法一解法二435
换底公式.1
指数式和对数式的互化.