题目内容
简算:
①
| ②1
| ③1
| ||||||||||||||||||||||
④
| ⑤1
| ⑥
|
考点:分数的简便计算
专题:运算定律及简算
分析:①利用减法的性质可得原式=
-
+
,再利用加法交换与结合律简算;
②④⑤⑥利用加法交换与结合律简算;
③利用减法的性质可得原式=1
-
-
,再利用加法交换与结合律简算.
5 |
7 |
8 |
15 |
2 |
7 |
②④⑤⑥利用加法交换与结合律简算;
③利用减法的性质可得原式=1
8 |
9 |
7 |
8 |
8 |
9 |
解答:
解:①
-(
-
)
=
-
+
=
+
-
=1-
=
;
②1
+
+
=1
+
+
=2+
=2
;
③1
-(
+
)
=1
-
-
=1
-
-
=1-
=
;
④
-
-
+
=
+
-
-
=1-
=
;
⑤1
-
-
=1
-
-
=1-
=
;
⑥
-
+
+
=
+
+
-
=
.
5 |
7 |
8 |
15 |
2 |
7 |
=
5 |
7 |
8 |
15 |
2 |
7 |
=
5 |
7 |
2 |
7 |
8 |
15 |
=1-
8 |
15 |
=
7 |
15 |
②1
5 |
12 |
5 |
15 |
7 |
12 |
=1
5 |
12 |
7 |
12 |
5 |
15 |
=2+
5 |
15 |
=2
1 |
3 |
③1
8 |
9 |
7 |
8 |
8 |
9 |
=1
8 |
9 |
7 |
8 |
8 |
9 |
=1
8 |
9 |
8 |
9 |
7 |
8 |
=1-
7 |
8 |
=
1 |
8 |
④
3 |
8 |
2 |
5 |
1 |
5 |
5 |
8 |
=
3 |
8 |
5 |
8 |
2 |
5 |
1 |
5 |
=1-
3 |
5 |
=
2 |
5 |
⑤1
3 |
4 |
13 |
20 |
3 |
4 |
=1
3 |
4 |
3 |
4 |
13 |
20 |
=1-
13 |
20 |
=
7 |
20 |
⑥
7 |
9 |
1 |
3 |
3 |
9 |
1 |
3 |
=
7 |
9 |
3 |
9 |
1 |
3 |
1 |
3 |
=
10 |
9 |
点评:完成本题要注意分析式中数据的特点,利用加法交换与结合律简算.
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