问题 解答题
1+
1
2
+
2
2
+
1
2
+
1
3
+
3
3
+
2
3
+
1
3
+…+
1
10
+
2
10
+…
+
9
10
+
10
10
+
9
10
+…+
1
10
=______.
答案

1+

1
2
+
2
2
+
1
2
+
1
3
+
3
3
+
2
3
+
1
3
+…+
1
10
+
2
10
+…
+
9
10
+
10
10
+
9
10
+…+
1
10

=1+

1
2
×(1+2+1)+
1
3
×(1+2+3+2+1)+
1
4
×(1+2+3+4+3+2+1)+…+
1
10
×(1+2+3+…+3+2+1)

=1+

1
2
×22+
1
3
×32+…+
1
10
×102

=1+2+3…+10

=(1+10)×10÷2

=55

故答案为:55.

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问答题 简答题