题目内容
计算(能简算的要简算)
(1)
×(
×7)
(2)72×
-
(3)4-
×
(4)
×
+
×
.
(1)
| 1 |
| 7 |
| 19 |
| 27 |
(2)72×
| 5 |
| 9 |
| 1 |
| 4 |
(3)4-
| 5 |
| 12 |
| 4 |
| 12 |
(4)
| 1 |
| 3 |
| 5 |
| 6 |
| 1 |
| 3 |
| 1 |
| 2 |
分析:(1)根据乘法交换律和结合律进行计算;
(2)先算乘法,再算减法;
(3)先算乘法,再算减法;
(4)根据乘法分配律进行计算.
(2)先算乘法,再算减法;
(3)先算乘法,再算减法;
(4)根据乘法分配律进行计算.
解答:解:(1)
×(
×7),
=(
×7)×
,
=
;
(2)72×
-
,
=40-
,
=39
;
(3)4-
×
,
=4-
,
=3
;
(4)
×
+
×
,
=
×(
+
),
=
×
,
=
.
| 1 |
| 7 |
| 19 |
| 27 |
=(
| 1 |
| 7 |
| 19 |
| 27 |
=
| 19 |
| 27 |
(2)72×
| 5 |
| 9 |
| 1 |
| 4 |
=40-
| 1 |
| 4 |
=39
| 3 |
| 4 |
(3)4-
| 5 |
| 12 |
| 4 |
| 12 |
=4-
| 5 |
| 36 |
=3
| 31 |
| 36 |
(4)
| 1 |
| 3 |
| 5 |
| 6 |
| 1 |
| 3 |
| 1 |
| 2 |
=
| 1 |
| 3 |
| 5 |
| 6 |
| 1 |
| 2 |
=
| 1 |
| 3 |
| 4 |
| 3 |
=
| 4 |
| 9 |
点评:此题主要考查分数的四则混合运算的运算顺序和应用运算定律进行简便计算.
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