问题
填空题
(2+
|
答案
(2+
)+(4+1 2
)+…+(2n+1 4
)1 2n
=2（1+2+…+n）+（
+1 2
+…+1 4
）1 2n
=2×
+n(n+1) 2
(1-1 2
)1 2 n 1- 1 2
=n2+n+1-
．1 2n
故答案为：n2+n+1-
．1 2n
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(2+
|
(2+
)+(4+1 2
)+…+(2n+1 4
)1 2n
=2（1+2+…+n）+（
+1 2
+…+1 4
）1 2n
=2×
+n(n+1) 2
(1-1 2
)1 2 n 1- 1 2
=n2+n+1-
．1 2n
故答案为：n2+n+1-
．1 2n