问题 解答题
下面各题怎样算简便就怎样算.
4
7
+
1
6
-
4
7
2-
7
9
-
2
9
3
5
+
7
8
+
2
5
5
6
-
3
10
+
1
6
-
7
10
2
5
+
1
3
+
3
5
5
12
+
5
9
-
5
12
答案

(1)

4
7
+
1
6
-
4
7

=

4
7
-
4
7
+
1
6

=

1
6

(2)2-

7
9
-
2
9

=2-(

7
9
+
2
9
),

=2-1,

=1;

(3)

3
5
+
7
8
+
2
5

=

3
5
+
2
5
+
7
8

=1+

7
8

=1

7
8

(4)

5
6
-
3
10
+
1
6
-
7
10

=(

5
6
+
1
6
)-(
3
10
+
7
10
),

=1-1,

=0;

(5)

2
5
+
1
3
+
3
5

=

2
5
+
3
5
+
1
3

=1+

1
3

=1

1
3

(6)

5
12
+
5
9
-
5
12

=

5
12
-
5
12
+
5
9

=

5
9

单项选择题 A1/A2型题
多项选择题