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

Redeem
TTP OnDemand GMAT Video Course
Featured Course

Target Test Prep GMAT OnDemand

Scott Woodbury-Stewart’s private virtual classroom — 400 hours of master-class video lessons for the GMAT Focus Edition.

  • 715+ score guarantee — highest in the industry (99th percentile)
  • 52 chapters · 1,500+ lessons · 4,000+ practice questions
  • 400 hours of video · 1,500+ instructor-led HD smartboard lessons
  • 300,000+ students accepted to Harvard, Stanford, Wharton, Booth & Sloan & more
  • 24/7 live support + weekly Zoom office hours with GMAT instructors
  • TTP AI Assist — 24/7 AI-powered virtual tutor for instant help
  • 1,200+ flashcards + AI-powered study assistant & daily calendar
  • OnDemand, LiveTeach & GMAT Bootcamp formats available
  • Also: GRE, SAT Math & Executive Assessment courses
  • MBA Admissions Consulting now available
  • 🏆 2025 EdTech Breakthrough Award: Test Prep Solution Provider of the Year
  • 200,000+ students served
  • 5-day free trial — $0 to start, no auto-billing, cancel anytime
★★★★★ 5.0 (559 reviews)
130-pt guarantee
$0 to start then $127/mo
Start Free 5-Day Trial Read 559 Reviews →

What is the value of x*?

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 63
Joined: Sat Dec 24, 2011 9:47 am
Location: India

by him1985 » Tue Mar 27, 2012 11:16 pm
B is sufficient.

using 1) we find two values for x : X=0,2
using 2) we find single value for x: X=2

So only 2nd is sufficient, 1st is not sufficient.
Himanshu Chauhan
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 626
Joined: Fri Dec 23, 2011 2:50 amFollowed by: 10 members
Location: Ahmedabad
Thanked: 31 times

by ronnie1985 » Thu Mar 29, 2012 10:13 am
(B) QED
Follow your passion, Success as perceived by others shall follow you
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Junior | Next Rank: 30 Posts
Posts: 14
Joined: Tue Jan 31, 2012 8:20 pm
Thanked: 9 times

by MQ0451 » Mon Apr 16, 2012 9:45 am
short cut for the OA when solving 2.

n* = n(n-1)
(x-1)*=x-2
(x-1)(x-2)=x-2 <- don't distribute, just divide each side by x-2
x-1=1
x=2
Sufficient.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Senior | Next Rank: 100 Posts
Posts: 44
Joined: Sun Apr 01, 2012 4:07 amFollowed by: 1 member

by chris558 » Sun Sep 09, 2012 8:51 am
1) x(x-1)=x
x^2-x=x
x^2-2x=0
x(x-2)=0
x=0 or (x-2)=0 -> x=2
x=0 or 2, INSUFFICIENT

2) (x-1)(x-1-1)=x-2
(x-1)(x-2)=x-2
(x^2-3x+2)=x-2
x^2-4x+4=0
(x-2)(x-2)=0
x=2
SUFFICIENT

Answer is B
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 171
Joined: Tue Jan 08, 2013 7:24 am
Thanked: 1 times

by rajeshsinghgmat » Thu Mar 21, 2013 3:47 am
D in Answer.

x-1=1

x=2
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Master | Next Rank: 500 Posts
Posts: 234
Joined: Tue Jul 16, 2013 9:00 am
Location: West Virginia
Thanked: 9 times

by Java_85 » Sun Oct 13, 2013 2:27 pm
B, Good question :)
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Newbie | Next Rank: 10 Posts
Posts: 3
Joined: Thu Nov 21, 2013 2:19 am

by swap-2 » Thu Jan 30, 2014 4:20 am
apoorva.srivastva wrote:For all integers n, n*=n (n-1). What is the value of x*?

(1.) X*=X
(2.) (X - 1 ) * = (X - 2)


OA after some discussion !! :)
OA- C
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Master | Next Rank: 500 Posts
Posts: 164
Joined: Sat Sep 20, 2014 10:26 pm
Thanked: 1 times

by jaspreetsra » Thu Dec 04, 2014 1:48 pm
DATA SUFFICIENCY QUESTION:
For all integers n, n* = n(n - 1). What is the value of x*?

1. x* = x (not sufficient)
2. (x - 1 )* = (x - 2) (sufficient)
Explanation:
(x - 1 )* = (x-1)(x-1-1)=(x-1)(x-2)
From (2)
(x - 1 )* = (x - 2)
=>(x-1)(x-2) = (x - 2)
or
(x-1) = 1
x=2

So, B.
What is right answer?
Question is what is the value of x*?
I think answer should be C bcz from (2) we have the value of x. From (1),we have x*=x.
Is it right?
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY

GMAT/MBA Expert

User avatar
Elite Legendary Member
Posts: 10392
Joined: Sun Jun 23, 2013 6:38 pmFollowed by: 511 members
Location: Palo Alto, CA
Thanked: 2867 times
GMAT Score:800

by [email protected] » Thu Dec 04, 2014 3:15 pm
Hi jaspreetsra,

Fact 1 gives us 2 different answers while Fact 2 gives us just 1 answer.

Final Answer: B

GMAT assassins aren't born, they're made,
Rich
Contact Rich at [email protected]
Image
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Newbie | Next Rank: 10 Posts
Posts: 1
Joined: Fri Jan 16, 2015 5:55 am

by smills » Fri Jan 30, 2015 7:33 am
Stupid question but I have to ask: Can someone please confirm what x* is? Is this the symbol for x squared??
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 2663
Joined: Wed Jan 14, 2015 8:25 amFollowed by: 128 members
Location: Boston, MA
Thanked: 1153 times
GMAT Score:770

by DavidG@VeritasPrep » Fri Jan 30, 2015 7:44 am
Not a stupid question at all. x* isn't an official mathematical symbol that exists outside of this problem - the problem defines the symbol. Here it's defined as
x* = x(x-1). x(x-1) then expands to x^2 - x.

(But if you were given 2*, we'd know that 2* = 2(2-1). If we were given 3*, we'd know that 3* = 3(3-1) and so on.)

The important thing to note is that the GMAT will sometimes define a symbol within the context of a problem.
Veritas Prep | GMAT Instructor

Veritas Prep Reviews
Save $100 off any live Veritas Prep GMAT Course
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pmFollowed by: 1906 members
Location: New York, NY
Thanked: 13060 times
GMAT Score:790

by GMATGuruNY » Fri Jan 30, 2015 8:04 am
smills wrote:Stupid question but I have to ask: Can someone please confirm what x* is? Is this the symbol for x squared??
Sometime the GMAT will use an arbitrary symbol to represent a particular FUNCTION.
For example:
@x = (x)(x+5).
Here, @x indicates the operation to be performed upon any value of x:
(x)(x+5).
Thus:
@1 = (1)(1+5)
@2 = (2)(2+5)
@3 = (3)(3+5)
And so on.

In the problem posted above:
x* = (x)(x-1).
Implication:
1* = (1)(1-1)
2* = (2)(2-1)
3* = (3)(3-1)
And so on.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
GMAT Instructor
Posts: 2630
Joined: Wed Sep 12, 2012 3:32 pmFollowed by: 119 members
Location: East Bay all the way
Thanked: 625 times
GMAT Score:780

by Matt@VeritasPrep » Mon Feb 09, 2015 2:06 am
smills wrote:Stupid question but I have to ask: Can someone please confirm what x* is? Is this the symbol for x squared??
This actually IS a mathematical symbol with a lot of different applications, most/all of which belong to math well out of the scope of the GMAT. (No, you aren't expected to know what a Hermitian adjoint is - the GMAT isn't that heinous!)

But none of the asterisk's fancy applications apply here: on the GMAT virtually any unfamiliar symbol (*, #, @, and even ^, which is an annoying internet way of indicating an exponent, but which doesn't properly mean that) doesn't have an inherent meaning and has to be defined. + and - mean what you think they do, but most other symbols are given a one-shot definition that only applies to that problem, and you aren't expected to know them before or remember them after.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Legendary Member
Posts: 518
Joined: Tue May 12, 2015 8:25 pm
Thanked: 10 times

by nikhilgmat31 » Mon Aug 03, 2015 6:36 am
Statement 1 gives X as 0 or 2 so X* can be 0 or 2
Statement 2 gives X as 2 so x* is 2 always.

Answer is B.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Junior | Next Rank: 30 Posts
Posts: 22
Joined: Wed Sep 20, 2017 5:42 pm
Thanked: 2 times

by pannalal » Thu Nov 30, 2017 4:15 am
madhan_dc wrote:As per one of the previous posts. I dont understand why we cannot divide each side by x in statement 1. Can anyone please explain this?

i divided both sides by x in statement 1 and got x =2

my answer was D.
Assume for a second that 5 = 7 (although it is not correct). Now, if you are allowed to multiply both sides with 0, both sides shows 0. So, 5 becomes equal to 7, though we know that 5 is not equal to 7. Thus, in an equation, whenever you multiply or divide by any value, the necessary condition is you are not multiplying or dividing by 0. I hope, this is clear to you.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply