题目内容
简算.
| 7-
| 11-
|
|
考点:分数的四则混合运算,运算定律与简便运算
专题:运算顺序及法则,运算定律及简算
分析:(1)(4)利用加法交换律与结合律简算;
(2)(3)利用减法的性质简算.
(2)(3)利用减法的性质简算.
解答:
解:(1)
+
+
+
=
+
+(
+
)+1
=2;
(2)7-
-
=7-(
+
)
=7-1
=6;
(3)11-
-
-
=11-(
+
+
)
=11-1
=10;
(4)
-
+
=
+
-
=1-
=
.
5 |
9 |
3 |
5 |
4 |
9 |
2 |
5 |
=
5 |
9 |
4 |
9 |
2 |
5 |
3 |
5 |
=2;
(2)7-
11 |
19 |
8 |
19 |
=7-(
11 |
19 |
8 |
19 |
=7-1
=6;
(3)11-
5 |
13 |
6 |
13 |
2 |
13 |
=11-(
5 |
13 |
6 |
13 |
2 |
13 |
=11-1
=10;
(4)
7 |
10 |
1 |
4 |
3 |
10 |
=
7 |
10 |
3 |
10 |
1 |
4 |
=1-
1 |
4 |
=
3 |
4 |
点评:分数混合运算的关键是抓住运算顺序,正确运用运算定律简算.
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