问题 解答题
化简:(1)
2
+
3
10
+
14
+
15
+
21

(2)
6
+4
3
+3
2
18
+
12
+3+
6
答案

(1)原式=

2
+
3
2
(
5
+
7
)+
3
(
5
+
7
)   

=

2
+
3
(
2
+
3
)(
5
+
7
)

=

1
5
+
7

=

7
-
5
7-5
=
1
2
(
7
-
5
);

(2)原式=

6
(1+2
2
+
3
6
(
3
+
2
)+  
3
(
3
+
2

=

6
(1+
2
+
2
+
3
)
3
(
3
+
2
)(
2
+1)

=

2
•(
1
3
+
2
+
1
2
+1
),

=

2
•(
3
-
2
+
2
-1),

=

6
-
2

单项选择题 A1/A2型题
单项选择题 B型题