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 →

then (x+1/x)^2 - (x-1/x)^2 =

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Problem Solving |

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 3835
Joined: Fri Apr 02, 2010 10:00 pmFollowed by: 523 members
Location: Milpitas, CA
Thanked: 1854 times
GMAT Score:770

by Anurag@Gurome » Tue Jul 17, 2012 10:36 pm
alex.gellatly wrote:If x does not equal 0, then (x+1/x)^2 - (x-1/x)^2 =
This can be solved in many ways,
Method 1:
(x + 1/x)² = (x² + 2 + 1/x²)
(x - 1/x)² = (x² - 2 + 1/x²)

Hence, (x + 1/x)² - (x - 1/x)² = 2 + 2 = 4

Method 2:
Let us assumes, (x + 1/x) = a and (x - 1/x) = b
Hence, (x + 1/x)² - (x - 1/x)² = (a² - b²) = (a - b)(a + b) = (2/x)*(2x) = 4

The correct answer is E.
Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)

Join Our Facebook Groups
GMAT with Gurome
https://www.facebook.com/groups/272466352793633/
Admissions with Gurome
https://www.facebook.com/groups/461459690536574/
Career Advising with Gurome
https://www.facebook.com/groups/360435787349781/
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pmFollowed by: 1906 members
Location: New York, NY
Thanked: 13060 times
GMAT Score:790

by GMATGuruNY » Wed Jul 18, 2012 12:03 pm
alex.gellatly wrote:If x does not equal 0, then (x+1/x)^2 - (x-1/x)^2 =

1/x
x
1
2
4
Let x=1.
Then ( x+1 / x )² - ( x-1 / x )² = ( 1+1 / 1 )² - ( 1-1 / 1 )² = 4-0 = 4.

The correct answer is E.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 435
Joined: Wed Nov 16, 2011 7:27 amFollowed by: 16 members
Thanked: 48 times

by alex.gellatly » Wed Jul 25, 2012 12:58 am
GMATGuruNY wrote:
alex.gellatly wrote:If x does not equal 0, then (x+1/x)^2 - (x-1/x)^2 =

1/x
x
1
2
4
Let x=1.
Then ( x+1 / x )² - ( x-1 / x )² = ( 1+1 / 1 )² - ( 1-1 / 1 )² = 4-0 = 4.

The correct answer is E.
If we let x = 1, shouldn't the correct answer be 4x (not 4). I got 4x, which is not an option.
Thanks
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Newbie | Next Rank: 10 Posts
Posts: 5
Joined: Wed May 30, 2012 6:41 am
Thanked: 1 times

by dineshsaini88 » Fri Jul 27, 2012 11:05 am
if u got 4x with x=1 put x=1 in 4x .. u ll get 4 .
cheers :)
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 435
Joined: Wed Nov 16, 2011 7:27 amFollowed by: 16 members
Thanked: 48 times

by alex.gellatly » Sat Jul 28, 2012 10:52 pm
dineshsaini88 wrote:if u got 4x with x=1 put x=1 in 4x .. u ll get 4 .
cheers :)
God... I'm an idiot. Haha, thanks.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1