题目内容
用你喜欢的方法计算.
|
|
1-
| ||||||||||||||||
15.8-(14.8+
|
|
3
|
分析:(1)(2)(3)题,通分计算;
(4)(6)运用减法的性质简算;
(5)运用加法交换律与结合律简算.
(4)(6)运用减法的性质简算;
(5)运用加法交换律与结合律简算.
解答:解:(1)
-
+
,
=
-
+
,
=
;
(2)
+
-
,
=
+
-
,
=
;
(3)1-
-
,
=1-(
+
),
=1-
,
=
;
(4)15.8-(14.8+
),
=15.8-14.8-
,
=1-
,
=
;
(5)
-
+
,
=
+
-
,
=1-
,
=
;
(6)3
-1
-1
,
=3
-(1
+1
),
=3
-3,
=
.
7 |
9 |
2 |
3 |
5 |
6 |
=
14 |
18 |
12 |
18 |
15 |
18 |
=
17 |
18 |
(2)
19 |
20 |
1 |
5 |
9 |
20 |
=
19 |
20 |
4 |
20 |
9 |
20 |
=
7 |
10 |
(3)1-
1 |
14 |
3 |
7 |
=1-(
1 |
14 |
6 |
14 |
=1-
1 |
2 |
=
1 |
2 |
(4)15.8-(14.8+
2 |
3 |
=15.8-14.8-
2 |
3 |
=1-
2 |
3 |
=
1 |
3 |
(5)
7 |
8 |
3 |
4 |
1 |
8 |
=
7 |
8 |
1 |
8 |
3 |
4 |
=1-
3 |
4 |
=
1 |
4 |
(6)3
7 |
8 |
4 |
9 |
5 |
9 |
=3
7 |
8 |
4 |
9 |
5 |
9 |
=3
7 |
8 |
=
7 |
8 |
点评:此题考查了通分计算,以及运用运算定律或性质简算.
练习册系列答案
相关题目