Last visit was: 07 Aug 2024, 09:33 It is currently 07 Aug 2024, 09:33
Toolkit
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

# A sequence is defined by an = (an-2)^2 - (an-1) for all terms n = 2, a

SORT BY:
Tags:
Show Tags
Hide Tags
Magoosh GMAT Instructor
Joined: 28 Dec 2011
Posts: 4490
Own Kudos [?]: 28904 [9]
Given Kudos: 130
Manager
Joined: 08 Sep 2016
Posts: 76
Own Kudos [?]: 54 [2]
Given Kudos: 25
Intern
Joined: 03 Jan 2017
Posts: 24
Own Kudos [?]: 15 [1]
Given Kudos: 5
Senior Manager
Joined: 26 Aug 2016
Posts: 446
Own Kudos [?]: 404 [0]
Given Kudos: 204
Location: India
GMAT 1: 690 Q50 V33
GMAT 2: 700 Q50 V33
GMAT 3: 730 Q51 V38
GPA: 4
WE:Information Technology (Consulting)
Re: A sequence is defined by an = (an-2)^2 - (an-1) for all terms n = 2, a [#permalink]
a1 =2;a2=1;a3=3;a4=-2;a5=11;a6=-7;a7=128, keep values to get the series , Hit Kudos if you liked it.
Senior Manager
Joined: 05 Jan 2017
Posts: 412
Own Kudos [?]: 288 [0]
Given Kudos: 15
Location: India
Re: A sequence is defined by an = (an-2)^2 - (an-1) for all terms n = 2, a [#permalink]
a1 =2
a2=1
a3=3
a4=-2
a5=11
a6=-7
a7=128.

Option E
Intern
Joined: 12 Jan 2018
Posts: 40
Own Kudos [?]: 48 [0]
Given Kudos: 36
Location: India
Concentration: General Management, Marketing
GMAT 1: 680 Q49 V32
WE:Engineering (Energy and Utilities)
Re: A sequence is defined by an = (an-2)^2 - (an-1) for all terms n = 2, a [#permalink]
a3= 4-1 = 3
a4= 1-3= -2
a5= 9 + 2= 11
a6= 4-11 = -7
a7= 121 + 7 = 128
Option E

Posted from my mobile device
Manager
Joined: 24 Mar 2015
Status:love the club...
Posts: 216
Own Kudos [?]: 112 [0]
Given Kudos: 527
Re: A sequence is defined by an = (an-2)^2 - (an-1) for all terms n = 2, a [#permalink]
mikemcgarry wrote:
A sequence is defined by $$a_{n} = (a_{n-2})^2 - (a_{n-1})$$ for all terms n > 2, and $$a_1 = 2$$ and $$a_2 = 1$$. What is the value of $$a_7$$?
(A) – 64
(B) – 7
(C) 38
(D) 88
(E) 128

This is the final problem from a set of challenging GMAT Quant practice question. For the whole collection, as well as the OE for this question, see:
Challenging GMAT Math Practice Questions

Mike

a3 = (a1)^2 - (a2)
= 3

a4 = (a2)^2 - (a3)
= -2

a5 = (a3)^2 - (a4)
= 11

a6 = (a4)^2 - (a5)
= -7

a7 = (a5)^2 - (a6)

thanks
Non-Human User
Joined: 09 Sep 2013
Posts: 34267
Own Kudos [?]: 859 [0]
Given Kudos: 0
Re: A sequence is defined by an = (an-2)^2 - (an-1) for all terms n = 2, a [#permalink]
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
Re: A sequence is defined by an = (an-2)^2 - (an-1) for all terms n = 2, a [#permalink]
Moderator:
Math Expert
94811 posts