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 →

knewton Q

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
Legendary Member
Posts: 1077
Joined: Mon Dec 13, 2010 1:44 amFollowed by: 33 members
Thanked: 118 times
GMAT Score:710
by bblast » Sat Aug 06, 2011 10:55 am
If m and n are negative numbers, which of the following numbers CANNOT be negative?

m^2 - n^2

n^2 - m^2

mn - m^2

n^3 - n

m^2 - 2mn + n^2


this can be solved by plugging numbers - looking for a more subtle approach-E
Cheers !!

Quant 47-Striving for 50
Verbal 34-Striving for 40

My gmat journey :
https://www.beatthegmat.com/710-bblast-s ... 90735.html
My take on the GMAT RC :
https://www.beatthegmat.com/ways-to-bbla ... 90808.html
How to prepare before your MBA:
https://www.youtube.com/watch?v=upz46D7 ... TWBZF14TKW_
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
Senior | Next Rank: 100 Posts
Posts: 49
Joined: Sun Jun 26, 2011 5:45 pm
Thanked: 2 times

by edge » Sat Aug 06, 2011 10:58 am
m² - 2mn + n² = (m - n)² > 0. E is the answer.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 1255
Joined: Fri Nov 07, 2008 2:08 pmFollowed by: 90 members
Location: St. Louis
Thanked: 312 times

by Tani » Sat Aug 06, 2011 12:05 pm
m^2 - 2mn + n^2 = (m-n)^2 Therefore it must be positive.
Tani Wolff
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 401
Joined: Tue May 24, 2011 1:14 amFollowed by: 5 members
Thanked: 37 times

by MBA.Aspirant » Sat Aug 06, 2011 2:51 pm
m^2 - 2mn + n^2 = (m-n) (m-n), since both are -ve, whether result is +ve or -ve, product is +ve
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 1255
Joined: Fri Nov 07, 2008 2:08 pmFollowed by: 90 members
Location: St. Louis
Thanked: 312 times

by Tani » Sat Aug 06, 2011 3:22 pm
all squares of real numbers are positive.
Tani Wolff
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Master | Next Rank: 500 Posts
Posts: 312
Joined: Tue Aug 02, 2011 3:16 pmFollowed by: 33 members
Location: New York City
Thanked: 130 times
GMAT Score:780

by gmatboost » Sun Aug 07, 2011 10:08 pm
Since you may not have realized that E was a perfect square, let's look at the other 4 choices too:

A. m^2 - n^2
We don't know whether m or n has the bigger absolute value, so this could go either way.

B. n^2 - m^2
This is basically the same answer as A, since we know the same info about m as we know about n. There is no way one of these could be right while the other is wrong.

C. mn - m^2
Factor: m(n-m)
m is negative, and (n-m) could be positive or negative, so the product could be negative

D. n^3 - n
Factor: n(n^2 - 1)
n is negative, and (n^2 - 1) could easily be positive, so the product could be negative
Greg Michnikov, Founder of GMAT Boost

GMAT Boost offers 250+ challenging GMAT Math practice questions, each with a thorough video explanation, and 100+ GMAT Math video tips, each 90 seconds or less.
It's a total of 20+ hours of expert instruction for an introductory price of just $10.
View sample questions and tips without signing up, or sign up now for full access.

Also, check out the most useful GMAT Math blog on the internet here.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 1077
Joined: Mon Dec 13, 2010 1:44 amFollowed by: 33 members
Thanked: 118 times
GMAT Score:710

by bblast » Mon Aug 08, 2011 12:06 am
Thank u Greg, I approached the problem the way u have solved.


Missed that E is a perfect square. Gotta tighten the screws of my cranium. :shock:
Cheers !!

Quant 47-Striving for 50
Verbal 34-Striving for 40

My gmat journey :
https://www.beatthegmat.com/710-bblast-s ... 90735.html
My take on the GMAT RC :
https://www.beatthegmat.com/ways-to-bbla ... 90808.html
How to prepare before your MBA:
https://www.youtube.com/watch?v=upz46D7 ... TWBZF14TKW_
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1