2/3+2/15+2/35+2/63+2/99+2/143.
问题描述:
+2 3
+2 15
+2 35
+2 63
+2 99
. 2 143
答
+2 3
+2 15
+2 35
+2 63
+2 99
,2 143
=1-
+1 3
-1 3
+1 5
-1 5
+1 7
-1 7
+1 9
-1 9
+1 11
-1 11
,1 13
=1-
,1 13
=
.12 13