题目内容
计算下面各题,能简算的要简算.
1+
|
2-
|
| ||||||||||||||||||
|
|
|
分析:(1)根据加法结合律进行计算;
(2)根据连减的性质进行计算;
(3)先算加法,再算减法;
(4)先算小括号里面的减法,再算括号外面的减法;
(5)根据加法交换律进行计算;
(6)根据加法交换律进行计算.
(2)根据连减的性质进行计算;
(3)先算加法,再算减法;
(4)先算小括号里面的减法,再算括号外面的减法;
(5)根据加法交换律进行计算;
(6)根据加法交换律进行计算.
解答:解:
(1)1+
-
,
=1+(
-
),
=1+0,
=1;
(2)2-
-
,
=2-(
+
),
=2-1,
=1;
(3)
+
-
,
=
-
,
=
;
(4)
-(
-
),
=
-
,
=-
;
(5)
+
+
,
=
+
+
,
=1+
,
=1
;
(6)
+
-
,
=
-
+
,
=
.
(1)1+
2 |
4 |
2 |
4 |
=1+(
2 |
4 |
2 |
4 |
=1+0,
=1;
(2)2-
2 |
7 |
5 |
7 |
=2-(
2 |
7 |
5 |
7 |
=2-1,
=1;
(3)
1 |
3 |
1 |
6 |
1 |
18 |
=
1 |
2 |
1 |
18 |
=
4 |
9 |
(4)
1 |
2 |
3 |
4 |
3 |
18 |
=
1 |
2 |
7 |
12 |
=-
1 |
12 |
(5)
2 |
5 |
3 |
7 |
3 |
5 |
=
2 |
5 |
3 |
5 |
3 |
7 |
=1+
3 |
7 |
=1
3 |
7 |
(6)
7 |
8 |
1 |
5 |
7 |
8 |
=
7 |
8 |
7 |
8 |
1 |
5 |
=
1 |
5 |
点评:四则运算,先弄清运算顺序,然后再进一步计算,能简算的要简算.
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