题目内容
将下列对数式化为指数式求x值:
(1)logx27=
;
(2)log2x=-
;
(3)log5(log2x)=0;
(4)x=log27
;
(5)x=log
16.
(1)logx27=
| 3 |
| 2 |
(2)log2x=-
| 2 |
| 3 |
(3)log5(log2x)=0;
(4)x=log27
| 1 |
| 9 |
(5)x=log
| 1 |
| 2 |
(1)∵logx27=
,∴x
=27,∴x=27
=32=9;
(2)log2x=-
,∴x=2-
=
=
;
(3)∵log5(log2x)=0,∴log2x=1,∴x=2;
(4)∵x=log27
,∴27x=
,化为33x=3-2,∴3x=-2,得到x=-
;
(5)∵x=log
16,∴(
)x=16,∴2-x=24,解得x=-4.
| 3 |
| 2 |
| 3 |
| 2 |
| 2 |
| 3 |
(2)log2x=-
| 2 |
| 3 |
| 2 |
| 3 |
| 1 | |||
|
| |||
| 2 |
(3)∵log5(log2x)=0,∴log2x=1,∴x=2;
(4)∵x=log27
| 1 |
| 9 |
| 1 |
| 9 |
| 2 |
| 3 |
(5)∵x=log
| 1 |
| 2 |
| 1 |
| 2 |
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