11+2+11+2+3+…+11+2+…+100=______.-数学

题目简介

11+2+11+2+3+…+11+2+…+100=______.-数学

题目详情

1
1+2
+
1
1+2+3
+…+
1
1+2+…+100
=______.
题型:解答题难度:中档来源:不详

答案

class="stub"1
1+2
+class="stub"1
1+2+3
+…+class="stub"1
1+2+…+100

=class="stub"1
(1+2)×2
2
+class="stub"1
(1+3)×3
2
+…+class="stub"1
(1+100)×100
2

=class="stub"2
2×3
+class="stub"2
3×4
+…class="stub"2
100×101

=2×(class="stub"1
2
-class="stub"1
3
+class="stub"1
3
-class="stub"1
4
+…+class="stub"1
100
-class="stub"1
101

=2×(class="stub"1
2
-class="stub"1
101

=2×class="stub"50
101

=class="stub"100
101

故答案为:class="stub"100
101

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