找规律计算:1/2+1/6+1/12+1/20+…+1/9900=_.
问题描述:
找规律计算:
+1 2
+1 6
+1 12
+…+1 20
=______. 1 9900
答
+1 2
+1 6
+1 12
+…+1 20
,1 9900
=(1-
)+(1 2
-1 2
)+(1 3
-1 3
)+(1 4
-1 4
)+…+(1 5
-1 99
),1 100
=1-
,1 100
=
.99 100