12×4+14×6+16×8+,…,+12n(2n+2)=()A.n2n+2B.n4n+4C.2nn+1D.2n2n+1-数学

题目简介

12×4+14×6+16×8+,…,+12n(2n+2)=()A.n2n+2B.n4n+4C.2nn+1D.2n2n+1-数学

题目详情

1
2×4
+
1
4×6
+
1
6×8
+,…,+
1
2n(2n+2)
=(  )
A.
n
2n+2
B.
n
4n+4
C.
2n
n+1
D.
2n
2n+1
题型:单选题难度:中档来源:不详

答案

class="stub"1
2×4
+class="stub"1
4×6
+class="stub"1
6×8
+…+class="stub"1
2n(2n+2)

=class="stub"1
2
[(class="stub"1
2
-class="stub"1
4
)+(class="stub"1
4
-class="stub"1
6
)+…+(class="stub"1
2n
-class="stub"1
2n+2
)]
=class="stub"1
2
class="stub"1
2
-class="stub"1
2n+2

=class="stub"1
2
class="stub"n
2n+2

=class="stub"n
4n+4

故选B

更多内容推荐