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GRE Prep Club Team Member
Joined: 20 Feb 2017
Posts: 2506
Given Kudos: 1055
GPA: 3.39
The sequence A is defined by the following relationship:
[#permalink]
06 May 2021, 00:21
06 May 2021, 00:21
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Question Stats:
55% (03:13) correct
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The sequence A is defined by the following relationship: \(A_n=A_{n-1}+(-1)^{n+1}(n)^2\) for all integer values \(n >1\). If \(A_1=1\) , what is \(A_{15}-A_{13}\) ?
A. 14
B. 29
C. 169
D. 196
E. 421
A. 14
B. 29
C. 169
D. 196
E. 421
Re: The sequence A is defined by the following relationship:
[#permalink]
07 May 2021, 02:13
07 May 2021, 02:13
2
Here
A15=A14+ (-1)^16* 15^2
A14=A13+ (-1)^15*14^2
from the above equations, we can replace the A14
and can get A15-A13= 15^2-14^2= 29 (B is the answer)
A15=A14+ (-1)^16* 15^2
A14=A13+ (-1)^15*14^2
from the above equations, we can replace the A14
and can get A15-A13= 15^2-14^2= 29 (B is the answer)
gmatclubot
Re: The sequence A is defined by the following relationship: [#permalink]
07 May 2021, 02:13
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