题目内容
(2008?福田区)用脱式计算:
(1)(
+
-
)×96;
(2)
÷[(
+
)×
].
(1)(
7 |
8 |
7 |
12 |
5 |
6 |
(2)
1 |
5 |
2 |
3 |
1 |
5 |
1 |
13 |
分析:(1)根据乘法分配律即可简便计算;
(2)先计算小括号里面的加法,再计算中括号里面的乘法,最后计算括号外的除法.
(2)先计算小括号里面的加法,再计算中括号里面的乘法,最后计算括号外的除法.
解答:解:(1)(
+
-
)×96,
=
×96+
×96-
×96
=12×7+8×7-5×16,
=(12+8)×7-5×16,
=140-80,
=60;
(2)
÷[(
+
)×
],
=
÷[(
+
)×
],
=
÷(
×
),
=
÷
,
=3.
7 |
8 |
7 |
12 |
5 |
6 |
=
7 |
8 |
7 |
12 |
5 |
6 |
=12×7+8×7-5×16,
=(12+8)×7-5×16,
=140-80,
=60;
(2)
1 |
5 |
2 |
3 |
1 |
5 |
1 |
13 |
=
1 |
5 |
10 |
15 |
3 |
15 |
1 |
13 |
=
1 |
5 |
13 |
15 |
1 |
13 |
=
1 |
5 |
1 |
15 |
=3.
点评:考查了分数的简便计算和分数的四则混合运算,要灵活运用运算律进行简便计算,同时注意四则混合运算的顺序和法则.
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