BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Target Test Prep · GMAT

Choose how you want to prepare

Learn live with an expert or move at your own pace. Every option includes the complete TTP study system.

★★★★★5.0559 reviews
GMATLiveTeach 7 seats left
Chris Peckover
NEXT LIVE COHORT

Oct 13 to Jan 7, 2027

with Chris Peckover

Schedule
Tue, Thu · 8:00 to 10:00 PM ET
Included
40 live hours + 6 months of GMAT OnDemand
  • Live instruction and real-time questions
  • Class recordings and assigned practice
View class & enroll
Limited cohort · enrollment openTarget Test Prep
EALiveTeach 5 seats left
Logan Thompson
EXECUTIVE ASSESSMENT

Sep 6 to Dec 6, 2026

with Logan Thompson

Schedule
Sun · 9:30 AM to 12:30 PM ET
Included
40 hours of live online classes plus six months of access to the complete TTP EA OnDemand course.
  • 165+ EA Score Guarantee
  • 4,100+ Quant, Verbal, and Integrated Reasoning practice questions
  • 400+ hours of in-depth video lessons
  • 3,000+ step-by-step video solutions
View EA class & enroll
Limited cohort · enrollment openTarget Test Prep
GMATOnDemand Start anytime
SELF-PACED MASTERCLASS

Target Test Prep GMAT OnDemand

Complete access from day one. Study on your schedule.

715+ score guarantee
$0to start then $127/mo
  • Personalized study plan and analytics
  • Thousands of lessons and practice questions
Start free 5-day trial
Read 559 reviewsTarget Test Prep

Compare the format, schedule, and included access before enrolling. Prices and seat counts shown reflect the supplied offer details.

what is the value of x

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 114
Joined: Tue Dec 23, 2008 5:33 pm
by showbu » Sun Jan 18, 2009 8:54 pm
Q3:
If n is an integer and x^n – x^(-n) = 0, what is the value of x ?
(1) x is an integer.
(2) n ≠ 0
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.

oa: Spoiler Code E
Last edited by showbu on Tue Jan 20, 2009 9:58 pm, edited 2 times in total.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Data Sufficiency |
Senior | Next Rank: 100 Posts
Posts: 79
Joined: Wed Feb 06, 2008 7:52 am
Thanked: 2 times
GMAT Score:620

by yalanand » Sun Jan 18, 2009 10:04 pm
My answer is : C


xn – x-n = 0

Hence x(n-1)=n

ie x=n/(n-1)

given n is an integer = (...-2,-1,0,1,2...)

1)x is an integer

x can be integer if n = 0, x=0/-1 = 0
x can be integer if n =2, x=2/2-1=2

Insuff

2) n ≠ 0


this alone cannot get us to the value of x, because x can be value, ineger or a real number

Insuff

toger we can infer n=2.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 114
Joined: Tue Dec 23, 2008 5:33 pm

by showbu » Sun Jan 18, 2009 11:13 pm
Sorry, my typo. Try again.
yalanand wrote:My answer is : C


xn – x-n = 0

Hence x(n-1)=n

ie x=n/(n-1)

given n is an integer = (...-2,-1,0,1,2...)

1)x is an integer

x can be integer if n = 0, x=0/-1 = 0
x can be integer if n =2, x=2/2-1=2

Insuff

2) n ≠ 0


this alone cannot get us to the value of x, because x can be value, ineger or a real number

Insuff

toger we can infer n=2.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 259
Joined: Thu Jan 18, 2007 8:30 pm
Thanked: 16 times

by amitabhprasad » Tue Jan 20, 2009 1:05 pm
I am getting "E"
Whats OA
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Junior | Next Rank: 30 Posts
Posts: 28
Joined: Sun Nov 02, 2008 12:35 pm
Thanked: 7 times

by sachinkr » Tue Jan 20, 2009 1:23 pm
IMO it should be B.

X^n - X ^(-n) = 0
=> X^n = X ^(-n)

A. X is an integer
This is true for all X when n = 0, so we cannot determine the value of X.
(Insufficient)

B. n ≠ 0
In this case, X can only be 1. There is no other value for which X^n = X^ (-n) .Sufficient.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Junior | Next Rank: 30 Posts
Posts: 17
Joined: Mon Jul 14, 2008 3:42 pm

by thechamp » Tue Jan 20, 2009 6:22 pm
'E' IMO
X^n - X ^(-n) = 0
=> X^n = X ^(-n) i.e. X^(2n)=1

A. X is an integer
n is unknown. If n=1, X^2=1 & X=+/-1

Insufficient

B. n ≠ 0
No info on X.

Insufficient

Taken together, X is integer & n ≠ 0
Whatever the value of n, X=+/-1

Insufficient.

Answer is E
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 435
Joined: Sat May 02, 2009 3:55 am
Thanked: 17 times

by madhur_ahuja » Sun Jul 05, 2009 9:38 am
Why is the answer not B in this case ?

X^2n=1. And If n<>0, this can only happen when x=1.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 2623
Joined: Mon Jun 02, 2008 3:17 amFollowed by: 355 members
Location: Montreal
Thanked: 1090 times
GMAT Score:780

by Ian Stewart » Sun Jul 05, 2009 10:20 am
x could be either 1 or -1, so the answer is E.
For online GMAT math tutoring, or to buy my higher-level Quant books and problem sets, contact me at ianstewartgmat at gmail.com

ianstewartgmat.com
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16207
Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members
Location: Vancouver, BC
Thanked: 5254 times
GMAT Score:770

by Brent@GMATPrepNow » Mon Jun 20, 2011 7:03 am
showbu wrote:Q3:
If n is an integer and x^n - x^(-n) = 0, what is the value of x ?
(1) x is an integer.
(2) n ≠ 0
OA: E
If we combine both statements, we see that there are some contradictory cases.
case a) x=1 and n=3, which means the answer to the target question is 1
case b) x=-1 and n=3, which means the answer to the target question is -1

Since we cannot answer the target question with certainty, the answer is E

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16207
Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members
Location: Vancouver, BC
Thanked: 5254 times
GMAT Score:770

by Brent@GMATPrepNow » Mon Jun 20, 2011 7:07 am
There is an important takeaway that is somewhat related to this question.

Some will assume that if X^a = X^b, then we can conclude that a=b. This is not the case.
There are 3 values for X where we cannot immediately conclude that a=b
These values for X are -1, 0 and 1

Examples:
0^3 = 0^5, but 3 does not equal 5
1^3 = 1^5, but 3 does not equal 5
(-1)^3 = (-1)^5, but 3 does not equal 5

Aside: If we know that a and/or b is negative, and we are told that X^a = X^b, it is not possible for X to equal 0, since 0^(negative number) is undefined.

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 1077
Joined: Mon Dec 13, 2010 1:44 amFollowed by: 33 members
Thanked: 118 times
GMAT Score:710

by bblast » Mon Jun 20, 2011 7:34 am
the equation solves out to :


x^n - 1/x^n = 0

(x^2n - 1)/x^n = 0

x^2n=1

thus x can be 1 or -1 given the statements.
Cheers !!

Quant 47-Striving for 50
Verbal 34-Striving for 40

My gmat journey :
https://www.beatthegmat.com/710-bblast-s ... 90735.html
My take on the GMAT RC :
https://www.beatthegmat.com/ways-to-bbla ... 90808.html
How to prepare before your MBA:
https://www.youtube.com/watch?v=upz46D7 ... TWBZF14TKW_
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1