问题 解答题
用自己喜欢的方法计算下面各题.
1-
5
12
-
7
12

5
12
+
7
8
-
7
8

7
8
+
7
27
+
20
27

1
3
+
2
7
+
2
3
+
4
7

5
11
+
2
7
+
6
11
+
5
7

2
3
-(
7
12
-
11
24
)
答案

(1)1-

5
12
-
7
12

=1-(

5
12
+
7
12
),

=1-1,

=0;

(2)

5
12
+
7
8
-
7
8

=

5
12
+(
7
8
-
7
8
),

=

5
12

(3)

7
8
+
7
27
+
20
27

=

7
8
+(
7
27
+
20
27
),

=

7
8
+1,

=1

7
8

(4)

1
3
+
2
7
+
2
3
+
4
7

=(

1
3
+
2
3
)+(
2
7
+
4
7
),

=1+

6
7

=1

6
7

(5)

5
11
+
2
7
+
6
11
+
5
7

=(

5
11
+
6
11
)+(
2
7
+
5
7
),

=1+1,

=2;

(6)

2
3
-(
7
12
-
11
24
),

=

2
3
-
3
24

=

13
24

单项选择题
单项选择题