探索并计算. 1/2=1/1×2=1−1/2 1/6=1/2×3=1/2−1/3 1/12=1/3×4=1/( )−1/( )… 计算:1/2+1/6+1/12+1/20+1/30+…+1/90.

问题描述:

探索并计算.

1
2
1
1×2
=1−
1
2

1
6
1
2×3
1
2
1
3

1
12
1
3×4
1
(   )
1
(   )

计算:
1
2
+
1
6
+
1
12
+
1
20
+
1
30
+…+
1
90

1
12
=
1
3×4
=
1
3
-
1
4

1
2
+
1
6
+
1
12
+
1
20
+
1
30
+…+
1
90

=
1
1×2
+
1
2×3
+
1
3×4
+
1
4×5
+
1
5×6
+…+
1
9×10

=
1
1
-
1
2
+
1
2
-
1
3
+
1
3
-
1
4
+…+
1
9
-
1
10

=1-
1
10

=
9
10