题目内容
下面各题,怎样算简便就怎样算
÷(
-
)×
3-
×
-
÷
+
×
+
×
÷2.
1 |
3 |
2 |
3 |
2 |
5 |
3 |
5 |
10 |
21 |
3 |
2 |
2 |
7 |
7 |
9 |
11 |
5 |
2 |
9 |
5 |
11 |
1 |
6 |
3 |
4 |
2 |
3 |
分析:根据四则混算的运算顺序,仔细审题,选择恰当的运用运算定律进行简算.
解答:解:①
÷(
-
)×
,
=
÷
×
,
=
×
×
,
=
;
②3-
×
-
,
=3-
-
,
=3-(
+
),
=3-1,
=2;
③
÷
+
×
,
=
×
+
×
,
=(
+
)×
,
=1×
,
=
;
④
+
×
÷2,
=
+
÷2,
=
+
,
=
.
1 |
3 |
2 |
3 |
2 |
5 |
3 |
5 |
=
1 |
3 |
4 |
15 |
3 |
5 |
=
1 |
3 |
15 |
4 |
3 |
5 |
=
3 |
4 |
②3-
10 |
21 |
3 |
2 |
2 |
7 |
=3-
5 |
7 |
2 |
7 |
=3-(
5 |
7 |
2 |
7 |
=3-1,
=2;
③
7 |
9 |
11 |
5 |
2 |
9 |
5 |
11 |
=
7 |
9 |
5 |
11 |
2 |
9 |
5 |
11 |
=(
7 |
9 |
2 |
9 |
5 |
11 |
=1×
5 |
11 |
=
5 |
11 |
④
1 |
6 |
3 |
4 |
2 |
3 |
=
1 |
6 |
1 |
2 |
=
1 |
6 |
1 |
4 |
=
5 |
12 |
点评:根据运算顺序计算,巧妙运用定律进行简算.
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