1手+13+1八+1…+1手gg7+11+11+13+1八+1…+1手gg7.-数学

题目简介

1手+13+1八+1…+1手gg7+11+11+13+1八+1…+1手gg7.-数学

题目详情

1
手+
1
3+
1
八+
1
…+
1
手gg7
+
1
1+
1
1+
1
3+
1
八+
1
…+
1
手gg7
题型:解答题难度:中档来源:不详

答案

首先推理:a-1+class="stub"1
a
=
a2-a+1
a
,a-2+class="stub"1
a-1+class="stub"1
a
=a-2+class="stub"a
a2-a+1
=
a3-3a2+3a-2
a2-a+1
=
a3+1-(a2-a+1)
a2-a+1
=a-2,
于是我们可以如到,class="stub"1
2001+class="stub"1
2006+class="stub"1
200我
=class="stub"1
2001
class="stub"1
2003+class="stub"1
2004+class="stub"1
2001
=class="stub"1
2003
,…,class="stub"1
3+class="stub"1
4+class="stub"1
1
=class="stub"1
3
class="stub"1
2+class="stub"1
3
=class="stub"3
class="stub"1
1+class="stub"1
3
=class="stub"3
4
class="stub"1
1+class="stub"3
4
=class="stub"4

class="stub"1
2+class="stub"1
3+class="stub"1
4+class="stub"1
…+class="stub"1
200我
class="stub"1
1+class="stub"1
1+class="stub"1
3+class="stub"1
4+class="stub"1
…+class="stub"1
200我
=class="stub"3
+class="stub"4
=1.

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