问题 解答题
用递等式计算.
3
8
+(
4
5
-
1
4
5
8
+
6
7
+(
3
8
-
6
7
1
4
-(
1
4
-
2
13
7
15
+
6
19
+
8
15
答案

(1)

3
8
+(
4
5
-
1
4
),

=

3
8
+
11
20

=

37
40

(2)

5
8
+
6
7
+(
3
8
-
6
7
),

=

5
8
+
6
7
+
3
8
-
6
7

=(

5
8
+
3
8
)+(
6
7
-
6
7
),

=1-0,

=1;

(3)

1
4
-(
1
4
-
2
13
),

=

1
4
-
1
4
+
2
13

=0+

2
13

=

2
13

(4)

7
15
+
6
19
+
8
15

=

7
15
+
8
15
+
6
19

=1+

6
19

=1

6
19

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