问题 填空题
设正整数m,n,满足m<n,且
1
m2+m
+
1
(m+1)2+(m+1)
+…+
1
n2+n
=
1
23
,则m+n的值是______.
答案

1
n2+n
=
1
n
-
1
n+1

1
m2+m
+
1
(m+1)2+(m+1)
+…+
1
n2+n

=

1
m
-
1
m+1
+
1
m+1
-
1
m+2
+…+
1
n
-
1
n+1

=

1
m
-
1
n+1
=
1
23
=
22
23×22

∴m=22,n+1=23×22=506,n=505,

m+n=527.

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