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 →

Algebra - Solving Equations

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Newbie | Next Rank: 10 Posts
Posts: 3
Joined: Tue Mar 08, 2016 2:51 pm
Location: Dublin, Ireland
by [email protected] » Sat Apr 09, 2016 6:46 am
The explanation to the solution of this question in the OG 2016 is not clear. Please help with a clearer explanation.

(X+1/X-1)^2

If X does not equal 0 or 1, and if X is replaced by 1/X everywhere in the above expression, then the resulting expression is equivalent to

A. (X+1/X-1)^2

B. (X-1/X+1)^2

C. (X^2+1)/(1-X^2)

D. (X^2-1)/(X^2+1)

E. -(X-1/X+1)^2
AYO
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |

GMAT/MBA Expert

User avatar
Elite Legendary Member
Posts: 10392
Joined: Sun Jun 23, 2013 6:38 pmFollowed by: 511 members
Location: Palo Alto, CA
Thanked: 2867 times
GMAT Score:800

by [email protected] » Sat Apr 09, 2016 8:48 am
Hi laiyemoa,

There's a full discussion of this question here:

https://www.beatthegmat.com/if-x-not-equ ... 59914.html

GMAT assassins aren't born, they're made,
Rich
Contact Rich at [email protected]
Image
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 » Sat Apr 09, 2016 8:51 am

(x+1)^2/(X-1)^2

If x is not = 0 or 1, and if x is replaced by 1/x everywhere in the expression above, then the resulting expression is equivalent to?

A) (x+1)^2/(x-1)^2
B) (x-1)^2/(x+1)^2
C) x^2+1/1-X^2
D) X^2-1/X^2+1
E) -(x-1)^2/-(X+1)^2
Let x=2, implying that -- everywhere in the given expression -- x must be replaced by 1/x = 1/2.

Replacing x with 1/2, we get:
(1/2 + 1)²/(1/2 - 1)² = (3/2)²/(-1/2)² = (9/4)/(1/4) = 9. This is our target.

Now plug x=2 into the answer choices to see which yields our target of 9.
A quick scan of the numerators reveals that only A is viable:
(x+1)²/(x-1)² = (2+1)²/(2-1)² = 9.

The correct answer is A.
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
Post new topic Post Reply
• Page 1 of 1