题目内容
| 计算下面各题,能简算的要简算. (
|
|
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|
20-
|
|
分析:(1)先算小括号里面的减法,再算括号外的除法;
(2)运用乘法分配律简算;
(3)先把除法变成乘法,再运用乘法分配律简算;
(4)先算除法,再算减法.
(2)运用乘法分配律简算;
(3)先把除法变成乘法,再运用乘法分配律简算;
(4)先算除法,再算减法.
解答:解:(1)(
-
)÷
,
=
÷
,
=
;
(2)
×
+
×
,
=(
+
)×
,
=
×
,
=
;
(3)
÷7+
×
,
=
×
+
×
,
=(
+
)×
,
=1×
,
=
;
(4)20-
÷
,
=20-
,
=19
.
| 3 |
| 4 |
| 1 |
| 8 |
| 5 |
| 12 |
=
| 5 |
| 8 |
| 5 |
| 12 |
=
| 3 |
| 2 |
(2)
| 1 |
| 7 |
| 6 |
| 13 |
| 8 |
| 13 |
| 1 |
| 7 |
=(
| 6 |
| 13 |
| 8 |
| 13 |
| 1 |
| 7 |
=
| 14 |
| 13 |
| 1 |
| 7 |
=
| 2 |
| 13 |
(3)
| 8 |
| 13 |
| 1 |
| 7 |
| 5 |
| 13 |
=
| 8 |
| 13 |
| 1 |
| 7 |
| 1 |
| 7 |
| 5 |
| 13 |
=(
| 8 |
| 13 |
| 5 |
| 13 |
| 1 |
| 7 |
=1×
| 1 |
| 7 |
=
| 1 |
| 7 |
(4)20-
| 7 |
| 9 |
| 7 |
| 8 |
=20-
| 8 |
| 9 |
=19
| 1 |
| 9 |
点评:本题考查了四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算定律进行简便计算.
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