题目内容
(2011?云阳县一模)
| 用递等式计算 (1)
|
(2)
| ||||||||||
(3)
|
(4)(
|
分析:(1)(2)(3)把除法改为乘法,约分即可;
(4)运用乘法分配律简算.
(4)运用乘法分配律简算.
解答:解:(1)
×
÷
,
=
×
×
,
=
;
(2)
÷
×10,
=
×
×10,
=15;
(3)
÷
×12,
=
×
×12,
=
;
(4)(
+
-
)×36,
=
×36+
×36-
×36,
=4+3-5,
=2.
| 7 |
| 8 |
| 4 |
| 5 |
| 3 |
| 4 |
=
| 7 |
| 8 |
| 4 |
| 5 |
| 4 |
| 3 |
=
| 14 |
| 15 |
(2)
| 5 |
| 6 |
| 5 |
| 9 |
=
| 5 |
| 6 |
| 9 |
| 5 |
=15;
(3)
| 3 |
| 14 |
| 15 |
| 28 |
=
| 3 |
| 14 |
| 28 |
| 15 |
=
| 24 |
| 5 |
(4)(
| 1 |
| 9 |
| 1 |
| 12 |
| 5 |
| 36 |
=
| 1 |
| 9 |
| 1 |
| 12 |
| 5 |
| 36 |
=4+3-5,
=2.
点评:在计算分数四则运算时,一般应把除法改为乘法,能简算要灵活简算.
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