题目内容
(1)计算:0.25-2+(
)-
-
lg16-2lg5+(
)0;
(2)解方程:log2(9x-5)=log2(3x-2)+2.
| 8 |
| 27 |
| 1 |
| 3 |
| 1 |
| 2 |
| 1 |
| 3 |
(2)解方程:log2(9x-5)=log2(3x-2)+2.
(1)0.25-2+(
)-
-
lg16-2lg5+(
)0
=16+
-lg4-lg25+1
=16+
-2+1
=
.
(2)∵log2(9x-5)=log2(3x-2)+2,
∴log2(9x-5)=log24(3x-2)
则原方程等价于
,
∴(3x)2-4•3x+3=0,即(3x-3)(3x-1)=0,
∵3x>2,∴3x=3,∴x=1.
经检验,得原方程的根为x=1.
| 8 |
| 27 |
| 1 |
| 3 |
| 1 |
| 2 |
| 1 |
| 3 |
=16+
| 3 |
| 2 |
=16+
| 3 |
| 2 |
=
| 33 |
| 2 |
(2)∵log2(9x-5)=log2(3x-2)+2,
∴log2(9x-5)=log24(3x-2)
则原方程等价于
|
∴(3x)2-4•3x+3=0,即(3x-3)(3x-1)=0,
∵3x>2,∴3x=3,∴x=1.
经检验,得原方程的根为x=1.
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