2/3+2/15+2/35+2/63+2/99+1/11.

问题描述:

2
3
+
2
15
+
2
35
+
2
63
+
2
99
+
1
11


2
3
+
2
15
+
2
35
+
2
63
+
2
99
+
1
11

=
2
1×3
+
2
3×5
+
2
5×7
+
2
7×9
+
2
9×11
+
1
11

=1-
1
3
+
1
3
-
1
5
+
1
5
-
1
7
+
1
7
-
1
9
+
1
9
-
1
11
+
1
11

=1.