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 →

If xy = 1

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Problem Solving |
Junior | Next Rank: 30 Posts
Posts: 28
Joined: Mon Jun 02, 2008 5:30 pm
Thanked: 3 times

by babachal » Thu Jun 12, 2008 3:23 pm
Hey, can you give us full question?
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Legendary Member
Posts: 631
Joined: Mon Feb 18, 2008 11:57 pmFollowed by: 3 members
Thanked: 29 times

by netigen » Thu Jun 12, 2008 3:38 pm
Question is what is the value of

2^(x + Y)^2)/2^(x - Y)^2
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 178
Joined: Wed May 14, 2008 3:51 pmFollowed by: 1 member
Thanked: 16 times
GMAT Score:99%+

by egybs » Thu Jun 12, 2008 4:02 pm
ahhhh.. in that case it's easy!

2^(x+y)^2 / 2^(x-y)^2

2^((x+y)^2 - (x-y)^2)

2^(x^2 + 2xy + y^2 - x^2 + 2xy - y^2)

2^(4xy)

which as we know is equal to 2^4... so 16.
Last edited by egybs on Thu Jun 12, 2008 4:21 pm, edited 1 time in total.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Junior | Next Rank: 30 Posts
Posts: 28
Joined: Mon Jun 02, 2008 5:30 pm
Thanked: 3 times

by babachal » Thu Jun 12, 2008 4:17 pm
egybs, you did mistake in the last step

2^(x^2+2xy+y^2-x^2+2xy-y^2)+2^4xy=2^4=16
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 178
Joined: Wed May 14, 2008 3:51 pmFollowed by: 1 member
Thanked: 16 times
GMAT Score:99%+

by egybs » Thu Jun 12, 2008 4:20 pm
oops! yep. i did.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 146
Joined: Thu Mar 27, 2008 2:13 pm
Thanked: 1 times

by s_raizada » Fri Jun 13, 2008 1:36 am
Hi guys,
question is not what you are calculating. See the screenshot of the question and it is form GMAT prep
Attachments
mathquestion.JPG
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 566
Joined: Fri Jan 04, 2008 11:01 am
Location: Philadelphia
Thanked: 31 times
GMAT Score:640

by AleksandrM » Fri Jun 13, 2008 9:19 am
Undifined or 25/9????? :?
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 178
Joined: Wed May 14, 2008 3:51 pmFollowed by: 1 member
Thanked: 16 times
GMAT Score:99%+

by egybs » Fri Jun 13, 2008 9:32 am
Can you give us the answer options...
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 » Fri Jun 13, 2008 11:23 am
As has been posted elsewhere, there's a typo in the question itself. The solution posted above by netigen, with the x and y terms in the exponents, presented the question in the way it's supposed to be written.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Junior | Next Rank: 30 Posts
Posts: 10
Joined: Tue Nov 04, 2008 1:25 pm

by GMAT dreamer » Tue Nov 18, 2008 12:16 pm
We can make things simpler...
If xy=1; it tells that x=1 and y=1, right?

so, 2^(1+1)^2/2^(1-1)^2=
2^2^2/2^0^2=
2^4/2^0=
16/1= 16

Very simple we put numbers.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Legendary Member
Posts: 2467
Joined: Thu Aug 28, 2008 6:14 pmFollowed by: 11 members
Thanked: 331 times

by cramya » Tue Nov 18, 2008 3:40 pm
If xy=1; it tells that x=1 and y=1, right?
In general if xy=1 does not necessarily mean x=1 and y=1 unless there are other properties about x and y also given that confirms the fact that x=1 y=1

To quote a few:

x=-1 y=-1 xy=1

x=5 y=1/5 xy =1

x=-5 y=-1/5 xy=1

Unless it says x and y are positive integers and xy=1 we cannot assume
x=1 and y=1

Hope this helps!
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Newbie | Next Rank: 10 Posts
Posts: 3
Joined: Mon Oct 15, 2007 6:16 pm

by rochy81 » Sun Aug 16, 2009 1:02 pm
Ahh, I was just stuck on this. I'm kicking myself...
Anyone happen to know what the difficulty of this question is?
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1