题目内容
计算下列各题,怎样简便就怎样算.
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15÷[
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(
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考点:分数的四则混合运算
专题:运算顺序及法则
分析:(1)把除法变为乘法,约分计算.
(2)(4)运用乘法分配律简算.
(3)先算小括号内的,再算中括号内的,最后算括号外的.
(5)先算小括号内的,然后把除法变为乘法,约分计算.
(6)把小数化为分出,把除法变为乘法,约分计算.
(2)(4)运用乘法分配律简算.
(3)先算小括号内的,再算中括号内的,最后算括号外的.
(5)先算小括号内的,然后把除法变为乘法,约分计算.
(6)把小数化为分出,把除法变为乘法,约分计算.
解答:
解:(1)
×
÷5
=
×
×
=
(2)
×(
+
)
=
×
+
×
=3+
=3
(3)15÷[
×(
-
)]
=15÷[
×
]
=15÷
=15×
=
(4)(
-
)×12
=
×12-
×12
=7-4
=3
(5)
÷(
-
)×3
=
÷
×3
=
×
×3
=2
(6)
×0.375÷
=
×
×
=
5 |
6 |
3 |
10 |
=
5 |
6 |
3 |
10 |
1 |
5 |
=
1 |
20 |
(2)
4 |
7 |
21 |
4 |
7 |
10 |
=
4 |
7 |
21 |
4 |
7 |
10 |
4 |
7 |
=3+
2 |
5 |
=3
2 |
5 |
(3)15÷[
1 |
3 |
1 |
2 |
1 |
9 |
=15÷[
1 |
3 |
7 |
18 |
=15÷
7 |
54 |
=15×
54 |
7 |
=
810 |
7 |
(4)(
7 |
12 |
1 |
3 |
=
7 |
12 |
1 |
3 |
=7-4
=3
(5)
4 |
9 |
5 |
6 |
1 |
6 |
=
4 |
9 |
2 |
3 |
=
4 |
9 |
3 |
2 |
=2
(6)
5 |
6 |
5 |
8 |
=
5 |
6 |
3 |
8 |
8 |
5 |
=
1 |
2 |
点评:考查了分数的四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算定律简便计算.
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