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#### Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here. # The nth term of the sequence a 1 , a 2 , a 3 , …, a n is def  Question banks Downloads My Bookmarks Reviews Important topics
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Moderator  Joined: 18 Apr 2015
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The nth term of the sequence a 1 , a 2 , a 3 , …, a n is def [#permalink]
Expert's post 00:00

Question Stats: 93% (00:38) correct 6% (01:35) wrong based on 32 sessions

The nth term of the sequence $$a_{1}$$ , $$a_{2}$$ , $$a_{3}$$ , …, an is defined as $$a_{n} = - (a_{n - 1} )$$. The first term $$a_{1} = – 1$$.

 Quantity A Quantity B $$a_{5}$$ $$1$$

A. The quantity in Column A is greater
B. The quantity in Column B is greater
C. The two quantities are equal
D. The relationship cannot be determined from the information given

Kudos for the right answer and solution.
[Reveal] Spoiler: OA

_________________ Manager Joined: 26 Jan 2018
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Kudos [?]: 110  , given: 3

Re: The nth term of the sequence a 1 , a 2 , a 3 , …, a n is def [#permalink]
1
KUDOS
On resolving we would get a sequence where all odd numbers in the series would be -1 and all even numbers would be +1. So a1, a3, a5, ..so on have values -1. a2, a4, a6, ... so on have +1.

Hence B is greater as a5 would have value of -1
Manager Joined: 27 Feb 2017
Posts: 189
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Kudos [?]: 49 , given: 15

Re: The nth term of the sequence a 1 , a 2 , a 3 , …, a n is def [#permalink]
can someone please explain this. I do not understand how we solve the terms GRE Prep Club Legend  Joined: 07 Jun 2014
Posts: 4857
GRE 1: Q167 V156 WE: Business Development (Energy and Utilities)
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Re: The nth term of the sequence a 1 , a 2 , a 3 , …, a n is def [#permalink]
2
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Expert's post
It is given that $$a_{1}=-1$$ and $$a_{n}=-a_{n-1}$$.

So $$a_{2}=-a_{1}=1$$.

And $$a_{3}=-a_{2}=-1$$.

So we can see every odd term is -1 and every even term is +1. So $$a_{5]$$ must be -1.

Hence option B is correct!
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Intern Joined: 15 May 2018
Posts: 38
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Kudos [?]: 5 , given: 1

Re: The nth term of the sequence a 1 , a 2 , a 3 , …, a n is def [#permalink]
Carcass wrote:
The nth term of the sequence a 1 , a 2 , a 3 , …, an is defined as $$a_{n} = -(a_{n - 1} )$$. The first term a1 equals –1.

 Quantity A Quantity B a5 1

A. The quantity in Column A is greater
B. The quantity in Column B is greater
C. The two quantities are equal
D. The relationship cannot be determined from the information given

Kudos for the right answer and solution.

My Answer is B
Intern  Joined: 04 May 2017
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Kudos [?]: 22 , given: 6

Re: The nth term of the sequence a 1 , a 2 , a 3 , …, a n is def [#permalink]
The sequence: -1 1 -1 1 -1 -> a5 = -1 -> B.
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Manager Joined: 23 Oct 2018
Posts: 57
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Kudos [?]: 0 , given: 0

Re: The nth term of the sequence a 1 , a 2 , a 3 , …, a n is def [#permalink]
thanks for the explanation Re: The nth term of the sequence a 1 , a 2 , a 3 , …, a n is def   [#permalink] 25 Oct 2018, 01:37
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