题目内容
怎样简便怎样计算. (1)
|
(2)1-
|
(3)
| ||||||||||||||||||
(4)
|
(5)4
|
(6)7-(
|
分析:(1)(3)(5)通分计算;
(2)运用减法的性质简算;
(4)运用加法交换律与结合律简算;
(6)先算括号内的,再算括号外的
(2)运用减法的性质简算;
(4)运用加法交换律与结合律简算;
(6)先算括号内的,再算括号外的
解答:解:(1)
+
-
,
=
+
-
,
=
;
(2)1-
-
,
=1-(
+
),
=1-1,
=0;
(3)
-
,
=
-
,
=
;
(4)
+
+
+
,
=(
+
)+(
+
),
=1+1,
=2;
(5)4
-2
-1
,
=4
-2
-1
,
=-
;
(6)7-(
-
),
=7-
,
=6
.
1 |
4 |
7 |
10 |
3 |
5 |
=
5 |
20 |
14 |
20 |
12 |
20 |
=
7 |
20 |
(2)1-
8 |
19 |
11 |
19 |
=1-(
8 |
19 |
11 |
19 |
=1-1,
=0;
(3)
5 |
6 |
2 |
3 |
=
5 |
6 |
4 |
6 |
=
1 |
6 |
(4)
5 |
8 |
9 |
17 |
3 |
8 |
8 |
17 |
=(
5 |
8 |
3 |
8 |
9 |
17 |
8 |
17 |
=1+1,
=2;
(5)4
7 |
18 |
3 |
4 |
7 |
8 |
=4
28 |
72 |
54 |
72 |
63 |
72 |
=-
17 |
72 |
(6)7-(
15 |
16 |
3 |
4 |
=7-
3 |
16 |
=6
13 |
16 |
点评:此题主要考查分数四则混合运算的运算顺序和应用运算定律进行简便计算.
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