题目内容
脱式计算:
×[
-(
-
)]
[
-(
-
)]÷
÷
+
×
.
8 |
9 |
3 |
4 |
7 |
16 |
1 |
4 |
[
1 |
2 |
3 |
4 |
3 |
5 |
7 |
10 |
7 |
9 |
11 |
5 |
2 |
9 |
5 |
11 |
分析:前两题按先算小括号里的,再算中括号里的,最后算括号外的顺序计算;最后一题可用乘法分配律简算.
解答:解:(1)
×[
-(
-
)],
=
×(
-
),
=
×
-
×
,
=
-
,
=
;
(2)[
-(
-
)]÷
,
=(
-
)÷
,
=
÷
,
=
;
(3)
÷
+
×
,
=
×
+
×
,
=
×(
+
),
=
×1,
=
.
8 |
9 |
3 |
4 |
7 |
16 |
1 |
4 |
=
8 |
9 |
3 |
4 |
3 |
16 |
=
8 |
9 |
3 |
4 |
8 |
9 |
3 |
16 |
=
2 |
3 |
1 |
6 |
=
1 |
2 |
(2)[
1 |
2 |
3 |
4 |
3 |
5 |
7 |
10 |
=(
1 |
2 |
3 |
20 |
7 |
10 |
=
7 |
20 |
7 |
10 |
=
1 |
2 |
(3)
7 |
9 |
11 |
5 |
2 |
9 |
5 |
11 |
=
7 |
9 |
5 |
11 |
2 |
9 |
5 |
11 |
=
5 |
11 |
7 |
9 |
2 |
9 |
=
5 |
11 |
=
5 |
11 |
点评:乘法分配律是常用的简算方法,有的题目变形之后或计算之后可以用乘法分配律计算.
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