D .3<a <4
8.方程2log3x =1
4的解是( )
A .x =1
9 B .x =x
3
C .x = 3
D .x =9
9.若log 2(log 3x )=log 3(log 4y )=log 4(log 2z )=0,则x +y +z 的值为(
) A .9 B .8
C .7
D .6
10.若102x =25,则x 等于( )
A .lg 15
B .lg5
C .2lg5
D .2lg 15
11.计算log 89·log 932的结果为( )
A .4 B.53 C.14 D.35
12.已知log a x =2,log b x =1,log c x =4(a ,b ,c ,x >0且≠1),则log x (abc )=( ) A.47 B.27 C.72 D.74
二.填空题
1. 2log 510+log 50.25=____.
2.方程log 3(2x -1)=1的解为x =_______.
3.若lg(ln x )=0,则x =_ ______.
4.方程9x -6·3x -7=0的解是_______
5.若log 34·log 48·log 8m =log 416,则m =________.
6.已知log a 2=m ,log a 3=n ,则log a 18=_______.(用m ,n 表示)
7.log 6[log 4(log 381)]=_______.
8.使对数式log (x -1)(3-x )有意义的x 的取值范围是_______
三.计算题
1.计算:
(1)2log 210+log 20.04 (2)lg3+2lg2-1lg1.2
(3)log 6112-2log 63+13
log 627 (4)log 2(3+2)+log 2(2-3);
2.已知log 34·log 48·log 8m =log 416,求m 的值.
对数与对数运算练习题答案
一.选择题
1. C 2. C 3. C 4. A 5. B 6. D 7. B 8 A 9. A 10. B11.B 12.D
二.填空题
1. 2
2. 2
3. e
4. x =log 37
5. 9
6. m +2n
7. 0
8. 1三.计算题
1.解: (1)2log 210+log 20.04=log 2(100×0.04)=log 24=2
(2)lg3+2lg2-1lg1.2=lg(3×4÷10)lg1.2=lg1.2lg1.2
=1 (3)log 6112-2log 63+13log 627=log 6112
-log 69+log 63 =log 6(112×19×3)=log 6136
=-2. (4)log 2(3+2)+log 2(2-3)
=log 2(2+3)(2-3)=log 21=0.
2. [解析] log 416=2,log 34·log 48·log 8m =log 3m =2,
∴m =9.