题目内容
(2012?霸州市模拟)
用递等式计算:
|
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(
|
|
分析:(1)(2)(4)法改为乘法,约分计算;
(3)把除法改为乘法,运用乘法分配律简算.
(3)把除法改为乘法,运用乘法分配律简算.
解答:解:(1)
×3÷
,
=
×
,
=
;
(2)
÷
÷
,
=
×
×
,
=
;
(3)(
+
)÷
,
=(
+
)×
,
=
;
(4)
÷
×4×
,
=
×
×4×
,
=5.
5 |
16 |
4 |
5 |
=
15 |
16 |
5 |
4 |
=
75 |
64 |
(2)
25 |
9 |
5 |
14 |
4 |
5 |
=
25 |
9 |
14 |
5 |
5 |
4 |
=
175 |
18 |
(3)(
7 |
8 |
13 |
16 |
13 |
16 |
=(
7 |
8 |
13 |
16 |
16 |
13 |
=
27 |
13 |
(4)
5 |
8 |
7 |
20 |
7 |
10 |
=
5 |
8 |
20 |
7 |
7 |
10 |
=5.
点评:本题考查了学生通过约分对分数四则混合运题目进行简算的能力.
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