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 →

Question from practice.beatthegmat

Problem Solving — algebra and arithmetic (GMAT Focus Edition)
Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Quantitative Reasoning |
Senior | Next Rank: 100 Posts
Posts: 57
Joined: Fri Jan 14, 2011 10:01 am
Thanked: 10 times

by djiddish98 » Tue May 24, 2011 4:17 am
x+y can't be 0, since a number over x+y = 6 (provided in statement 1).

This is one of those problems where you can solve for x-y by reducing a statement

Statement 1: x^2 - y^2 -> (x-y)(x+y). We can cancel out the x+y portions of the statement and we're left with x-y = 6

Statement 2: we can consolidate to (x-y)^2 = 36. However, x-y could equal -6 or 6, so we're not quite sure yet.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 1309
Joined: Mon Apr 04, 2011 5:34 amFollowed by: 123 members
Location: India
Thanked: 310 times
GMAT Score:750

by cans » Sun May 29, 2011 9:40 pm
A) (x2-y2)/(x+y) = (x-y)(x+y)/(x+y)
If we consider x+y = 0, we get 0/0 which is indeterminate. But we know that L.H.S = 6,
It means x+y is not equal to 0, and thus x-y =6
Sufficient.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
GMAT Instructor
Posts: 1035
Joined: Fri Dec 17, 2010 11:13 amFollowed by: 365 members
Location: Los Angeles, CA
Thanked: 474 times

by VivianKerr » Thu Jun 02, 2011 12:39 pm
Quick thought: I always like to keep in mind for this type of DS that we will never need to solve for the variables independently. Finding x - y does not mean we have to be able to find x and y separately.
Vivian Kerr
GMAT Rockstar, Tutor
https://www.GMATrockstar.com
https://www.yelp.com/biz/gmat-rockstar-los-angeles

Former Kaplan and Grockit instructor, freelance GMAT content creator, now offering affordable, effective, Skype-tutoring for the GMAT at $150/hr. Contact: [email protected]

Thank you for all the "thanks" and "follows"! :-)
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1