问题 解答题
下列各题怎样简便就怎样算
1
7
+
9
11
+
3
7
+
2
11
1
2
-(
3
4
-
3
8
12-
7
10
-
3
10
5
6
-(
1
2
+
1
3
7
15
+
4
9
+
8
15
答案

(1)

1
7
+
9
11
+
3
7
+
2
11

=(

1
7
+
3
7
)+(
2
11
+
9
11
),

=

4
7
+1,

=1

4
7

(2)

1
2
-(
3
4
-
3
8
),

=

1
2
-
3
8

=

1
8

(3)12-

7
10
-
3
10

=12-(

7
10
+
3
10
),

=12-1,

=11;

(4)

5
6
-(
1
2
+
1
3
),

=

5
6
-
5
6

=0;

(5)

7
15
+
4
9
+
8
15

=

7
15
+
8
15
+
4
9

=1+

4
9

=1

4
9

单项选择题 A3型题
单项选择题