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 Starts Oct 17
Chris Peckover, Target Test Prep GMAT expert
LIVE ONLINE CLASSES

Get Ready for GMAT Test Day Faster with Live Online Classes

with Chris Peckover, 100th-Percentile GMAT Scorer

Oct 17 · Chris Peckover
Sat · 11:00 AM to 2:00 PM ET
Oct 20 · Chris Peckover
Tue, Thu · 8:00 to 10:00 PM ET
Oct 25 · Josh Braslow
Sun · 1:00 to 4:00 PM ET
Included
40 hours of live online classes + 6 months of TTP OnDemand
  • Attend the first class for free
  • Every class is recorded, so you never fall behind
View classes & enroll
Limited seats availableTarget Test Prep
EALiveTeachOnDemand 5 seats left Start anytime
EXECUTIVE ASSESSMENT

Target Test Prep EA OnDemand

Self-paced EA prep. Study on your schedule.

Logan Thompson
EXECUTIVE ASSESSMENT

Sep 6 to Dec 6, 2026

with Logan Thompson

165+ EA score guarantee
$05-day trial no automatic billing
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 Start free 5-day trial
Limited cohort · enrollment openTrial includes full course accessTarget 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.

ds prep.

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Newbie | Next Rank: 10 Posts
Posts: 4
Joined: Mon Nov 05, 2007 5:47 am
by galaxis09 » Mon Dec 03, 2012 3:26 pm
I know this problem has been posted before, but I cannot figure out where I am going wrong.
If 0<x<y, what is the value of (x+y)^2 / (x-y)^2


(1) x^2 + y^2 = 3xy

(2) xy = 3 .


When multiplied out we get x^2+2xy+y^2/x^2-2xy+y^2. Why can I not subtract the divisor and be left with 4xy. xy=3, 3*4=12
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Data Sufficiency |
User avatar
Master | Next Rank: 500 Posts
Posts: 145
Joined: Tue Jan 31, 2012 6:50 amFollowed by: 2 members
Location: New Delhi
Thanked: 16 times
GMAT Score:760

by nisagl750 » Tue Dec 04, 2012 3:03 am
galaxis09 wrote:I know this problem has been posted before, but I cannot figure out where I am going wrong.
If 0<x<y, what is the value of (x+y)^2 / (x-y)^2


(1) x^2 + y^2 = 3xy

(2) xy = 3 .

Statement 1: We have (x^2+2xy+y^2) / (x^2-2xy+y^2)

subsitute the value from statement 1: x^2+y^2 = 3xy, we get
(3xy+2xy)/(3xy-2xy) = 5xy/xy = 5 (Since both x & y are positive)
Sufficient

Statement 2: We have (x^2+2xy+y^2) / (x^2-2xy+y^2)

subsitute the value from statement 2: xy=3, we get
(x^2+2*3+y^2) / (x^2-2*3+y^2)

= x^2+y^2+6/x^2+y^2-6
Since we do not know the values of X & Y
[spoiler]Do not assume x=1, y=3 as xy=3, It is nowhere written both are integers. x can be 1/3 and y can be 9[/spoiler]
Insufficient

IMO Answer is A
Wat is the OA?
Why can I not subtract the divisor and be left with 4xy. xy=3, 3*4=12
I didn't quite get your question. What from do you want to subtract the divisor?
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 » Tue Dec 04, 2012 6:53 am
galaxis09 wrote: If 0<x<y, what is the value of (x+y)^2 / (x-y)^2

(1) x^2 + y^2 = 3xy
(2) xy = 3
Target question: What is the value of (x+y)^2 / (x-y)^2

If we expand the numerator and denominator, we get [x^2 + 2xy + y^2] / [x^2 - 2xy + y^2], so we can rephrase the target question.

Rephrased target question: What is the value of [x^2 + 2xy + y^2] / [x^2 - 2xy + y^2]?

Statement 1: x^2 + y^2 = 3xy
Since x^2 + y^2 appears in the numerator and the denominator of the rephrased target question, we can replace x^2 + y^2 with 3xy to get:
What is the value of [3xy + 2xy] / [3xy - 2xy]?
This simplifies to be 5xy/xy, which equals 5 (since neither x nor y equal 0)
Since the expression evaluates to be one distinct value, we can answer the target question with certainty.
So statement 1 is SUFFICIENT

Statement 2: xy = 3
Since xy appears in the numerator and the denominator of the rephrased target question, we can replace xy with 3 to get:
What is the value of [x^2 + 2(3) + y^2]/[x^2 - 2(3) + y^2]?
This simplifies to be [x^2 + y^2 + 6]/[x^2 + y^2 - 6]
Can we simplify this expression further so that we get only one distinct value?
No.
The value of the expression can vary, depending on the values of x and y. To demonstrate this, consider these two case:
Case a: x=0.5, y=6 in which case [x^2 + 2xy + y^2] / [x^2 - 2xy + y^2] = -13/11
Case b: x=1, y=3 in which case [x^2 + 2xy + y^2] / [x^2 - 2xy + y^2] = -2
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT

Answer = A

Cheers,
Brent
Last edited by Brent@GMATPrepNow on Thu Dec 13, 2012 8:47 am, edited 2 times in total.
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 » Tue Dec 04, 2012 7:00 am
galaxis09 wrote: When multiplied out we get x^2+2xy+y^2/x^2-2xy+y^2. Why can I not subtract the divisor and be left with 4xy. xy=3, 3*4=12
I see that (x^2 + 2xy + y^2) - (x^2 - 2xy + y^2) = 4xy, but this doesn't mean that (x^2 + 2xy + y^2)/(x^2 - 2xy + y^2) = 4xy as well.

In one case we're subtracting and in the other case, we're dividing.

Similarly, 6/2 does not equal 6 - 2

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
Master | Next Rank: 500 Posts
Posts: 145
Joined: Tue Jan 31, 2012 6:50 amFollowed by: 2 members
Location: New Delhi
Thanked: 16 times
GMAT Score:760

by nisagl750 » Tue Dec 04, 2012 8:07 am
Brent@GMATPrepNow wrote:
galaxis09 wrote: If 0<x<y,
Case a: x=3, y=1 in which case [x^2 + 2xy + y^2] / [x^2 - 2xy + y^2] = 2
X can't be greater than Y as given in the question...
Case a: can be X=1/3, Y=9 which will give a different value for the above expression.

Either ways, Answer A
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 » Tue Dec 04, 2012 8:11 am
nisagl750 wrote:
Brent@GMATPrepNow wrote:
galaxis09 wrote: If 0<x<y,
Case a: x=3, y=1 in which case [x^2 + 2xy + y^2] / [x^2 - 2xy + y^2] = 2
X can't be greater than Y as given in the question...
Case a: can be X=1/3, Y=9 which will give a different value for the above expression.

Either ways, Answer A
Ah, good catch - thanks.

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Junior | Next Rank: 30 Posts
Posts: 15
Joined: Mon Nov 26, 2012 1:14 am
Thanked: 1 times

by sri_r » Thu Dec 13, 2012 1:25 am
Hi,

Is the correct answer C ?
My reasoning is:
from (1) => x^2+y^2 = 3xy
=> x^2 + y^2 -2xy = xy
=> (x-y)^2 = xy

from(2) => xy = 3
so (x-y)^2 = 3

Similarly (x+y)^2 = (x-y)^2 + 4xy
=> 3 + 4*3
=> 15

Therefore answer = 15/3 = 5




Brent@GMATPrepNow wrote:
galaxis09 wrote: If 0<x<y, what is the value of (x+y)^2 / (x-y)^2

(1) x^2 + y^2 = 3xy
(2) xy = 3
Target question: What is the value of (x+y)^2 / (x-y)^2

If we expand the numerator and denominator, we get [x^2 + 2xy + y^2] / [x^2 - 2xy + y^2], so we can rephrase the target question.

Rephrased target question: What is the value of [x^2 + 2xy + y^2] / [x^2 - 2xy + y^2]?

Statement 1: x^2 + y^2 = 3xy
Since x^2 + y^2 appears in the numerator and the denominator of the rephrased target question, we can replace x^2 + y^2 with 3xy to get:
What is the value of [3xy + 2xy] / [3xy - 2xy]?
This simplifies to be 5xy/xy, which equals 5 (since neither x nor y equal 0)
Since the expression evaluates to be one distinct value, we can answer the target question with certainty.
So statement 2 is NOT SUFFICIENT

Statement 2: xy = 3
Since xy appears in the numerator and the denominator of the rephrased target question, we can replace xy with 3 to get:
What is the value of [x^2 + 2(3) + y^2]/[x^2 - 2(3) + y^2]?
This simplifies to be [x^2 + y^2 + 6]/[x^2 + y^2 - 6]
Can we simplify this expression further so that we get only one distinct value?
No.
The value of the expression can vary, depending on the values of x and y. To demonstrate this, consider these two case:
Case a: x=3, y=1 in which case [x^2 + 2xy + y^2] / [x^2 - 2xy + y^2] = 2
Case b: x=1, y=3 in which case [x^2 + 2xy + y^2] / [x^2 - 2xy + y^2] = -2
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT

Answer = A

Cheers,
Brent
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 » Thu Dec 13, 2012 8:55 am
sri_r wrote:Hi,

Is the correct answer C ?
My reasoning is:
from (1) => x^2+y^2 = 3xy
=> x^2 + y^2 -2xy = xy
=> (x-y)^2 = xy
You've determined that (x-y)^2 = xy, but we can also do some some work with (x+y)^2
(x+y)^2 = x^2 + 2xy + y^2
= 3xy + 2xy [I replaced x^2 + y^2 with 3xy)
= 5xy

So, (x+y)^2 = 5xy and (x-y)^2 = xy
This means that (x+y)^2 / (x-y)^2 = 5xy/xy = 5
Statement 1 is sufficient

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1