Live GMAT classes with Target Test Prep start Nov 21 and Nov 22. First class free.

See classes
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.

Newsweek Readers’ Choice Awards 2026 winner: Target Test Prep, #1 Test Prep

Target Test Prep was voted #1 Best Test Prep in the 2026 Newsweek Readers’ Choice™ Awards.

★★★★★5.0563 reviews
GMATLiveTeachStarts Nov 22
Josh Braslow, Target Test Prep GMAT expert
LIVE ONLINE CLASSES

Get Ready for GMAT Test Day Faster with Live Online Classes

with Josh Braslow, 20+ years in test prep

Nov 22 · Josh Braslow
Sun · 9:30 AM to 12:30 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
EALiveTeachOnDemandStart anytime
EXECUTIVE ASSESSMENT

Target Test Prep EA OnDemand

Self-paced EA prep. Study on your schedule.

EXECUTIVE ASSESSMENT

with

165+ EA score guarantee
$05-day trial no automatic billing
Schedule
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
GMATOnDemandStart 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

If 2^{(x+y)^2} / 2^{(x-y)^2} = 2, what is the value of xy?

Expert replies
by swerve » Tue Feb 13, 2018 7:57 am
$$If\ \frac{2^{\left(x+y\right)^2}}{2^{\left(x-y\right)^2}}=2,$$ What is the value of xy?

(A) -1/4
(B) 1/2
(C) 0
(D) 1/4
(E) 1/2

The OA is D.

Would any expert please break down the steps to solve this PS question, step by step? I tried to solve it but I can't get the correct answer. I need your help. Thanks.
Join the discussion
Source: — Problem Solving |

by Brent@GMATPrepNow » Tue Feb 13, 2018 9:22 am
swerve wrote:$$If\ \frac{2^{\left(x+y\right)^2}}{2^{\left(x-y\right)^2}}=2,$$ What is the value of xy?

(A) -1/4
(B) 1/2
(C) 0
(D) 1/4
(E) 1/2
(x + y)² = x² + 2xy + y²
(x - y)² = x² - 2xy + y²

Given: 2^(x + y)²/2^(x - y)² = 2
Expand both exponents to get: 2^(x² + 2xy + y²)/2^(x² - 2xy + y²) = 2
Apply Quotient Law to get: 2^(4xy) = 2
In other words, 2^(4xy) = 2^1
This means that: 4xy = 1
Divide both sides by 4 to get: xy = 1/4

Answer: D

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image
Join the discussion

by EconomistGMATTutor » Tue Feb 13, 2018 11:45 am
$$If\ \frac{2^{\left(x+y\right)^2}}{2^{\left(x-y\right)^2}}=2,$$ What is the value of xy?

(A) -1/4
(B) 1/2
(C) 0
(D) 1/4
(E) 1/2

The OA is D.

Would any expert please break down the steps to solve this PS question, step by step? I tried to solve it but I can't get the correct answer. I need your help. Thanks.
Hi swerve,
Let's take a look at your question.

$$\frac{2^{\left(x+y\right)^2}}{2^{\left(x-y\right)^2}}=2 ... (i)$$
Let's evaluate the square of binomials in the exponent of 2, using polynomial identities:
$$\left(x+y\right)^2=x^2+2xy+y^2$$
$$\left(x-y\right)^2=x^2-2xy+y^2$$
Eq(i) will become:
$$\frac{2^{\left(x^2+2xy+y^2\right)}}{2^{\left(x^2-2xy+y^2\right)}}=2$$
$$2^{\left(x^2+2xy+y^2\right)-\left(x^2-2xy+y^2\right)}=2$$
$$2^{x^2+2xy+y^2-x^2+2xy-y^2}=2$$
$$2^{2xy+2xy}=2$$
$$2^{4xy}=2$$
$$2^{4xy}=2^1$$
Since bases on both sides of the equation are the same, we can equate the exponents, hence,
$$4xy=1$$
$$xy=\frac{1}{4}$$
Therefore, Option D is correct.

Hope it helps.
I am available if you'd like any follow up.
GMAT Prep From The Economist
We offer 70+ point score improvement money back guarantee.
Our average student improves 98 points.

Image
Join the discussion

by [email protected] » Tue Feb 13, 2018 5:12 pm
Hi swerve,

Since both the numerator and denominator of the fraction are 'base 2', we ultimately need a fraction that simplifies to (2^1)/(2^0) = 2.

Algebraically, this means that (X+Y) has to be '1 greater' than (X-Y), so we can set up the following equation:

X + Y = X - Y + 1

Then combine like terms and simplify (the X's cancel out):

2Y = 1
Y = 1/2

Plugging that value into the numerator, we have:

X + 1/2 = 1
X = 1/2

Thus, (X)(Y) = (1/2)(1/2) = 1/4

Final Answer: D

GMAT assassins aren't born, they're made,
Rich
Contact Rich at [email protected]
Image
Join the discussion