题目内容
化简求值:
(1)0.064
-(
)0+16
+0.36
(2)log2.56.25+lg
+ln
+2log23.
(1)0.064
1 |
3 |
1 |
8 |
3 |
4 |
1 |
2 |
(2)log2.56.25+lg
1 |
100 |
e |
分析:(1)化小数为分数,然后运用有理指数幂的运算性质化简求值;
(2)把对数的真数化为乘方的形式,然后直接利用对数的运算性质化简.
(2)把对数的真数化为乘方的形式,然后直接利用对数的运算性质化简.
解答:解:(1)0.064
-(
)0+16
+0.36
=[(0.4)3]
-1+(24)
+[(0.6)2]
=0.4-1+8+0.6
=8;
(2)log2.56.25+lg
+ln
+2log23
=log2.5(2.5)2+lg10-2+
+3
=2-2+
+3
=
.
1 |
3 |
1 |
8 |
3 |
4 |
1 |
2 |
=[(0.4)3]
1 |
3 |
3 |
4 |
1 |
2 |
=0.4-1+8+0.6
=8;
(2)log2.56.25+lg
1 |
100 |
e |
=log2.5(2.5)2+lg10-2+
1 |
2 |
=2-2+
1 |
2 |
=
7 |
2 |
点评:本题考查了有理指数幂的化简与求值,考查了对数的运算性质,是基础的运算题.
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