题目内容
计算下面各题,能简便计算的要简便计算.
-
-
(
-
)÷
9÷
-
÷
÷
-
×
.
7 |
4 |
1 |
10 |
9 |
10 |
(
6 |
7 |
3 |
5 |
9 |
5 |
9÷
6 |
7 |
7 |
6 |
1 |
9 |
19 |
13 |
7 |
5 |
6 |
13 |
5 |
7 |
分析:(1)可运用“a-b-c=a-(b+c)”的规律进行简便计算;
(2)(3)(4)可运用乘法分配律进行计算比较简便.
(2)(3)(4)可运用乘法分配律进行计算比较简便.
解答:解:(1)
-
-
,
=
-(
+
),
=
-1,
=
;
(2)(
-
)÷
,
=(
-
)×
,
=
×
-
×
,
=
-
,
=
-
,
=
;
(3)9÷
-
÷
,
=9×
-
×9,
=0;
(4)
÷
-
×
,
=
×
-
×
,
=
×(
-
),
=
×1,
=
.
7 |
4 |
1 |
10 |
9 |
10 |
=
7 |
4 |
1 |
10 |
9 |
10 |
=
7 |
4 |
=
3 |
4 |
(2)(
6 |
7 |
3 |
5 |
9 |
5 |
=(
6 |
7 |
3 |
5 |
5 |
9 |
=
6 |
7 |
5 |
9 |
3 |
5 |
5 |
9 |
=
10 |
21 |
1 |
3 |
=
10 |
21 |
7 |
21 |
=
1 |
7 |
(3)9÷
6 |
7 |
7 |
6 |
1 |
9 |
=9×
7 |
6 |
7 |
6 |
=0;
(4)
19 |
13 |
7 |
5 |
6 |
13 |
5 |
7 |
=
19 |
13 |
5 |
7 |
6 |
13 |
5 |
7 |
=
5 |
7 |
19 |
13 |
6 |
13 |
=
5 |
7 |
=
5 |
7 |
点评:此题是考查四则混合运算,要仔细观察算式的特点,灵活运用一些定律进行简便计算.

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