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 →

the value of x^4 – y^4

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
GMAT Instructor
Posts: 3650
Joined: Wed Jan 21, 2009 4:27 amFollowed by: 80 members
Location: India
Thanked: 267 times
GMAT Score:760
by sanju09 » Fri Oct 15, 2010 10:15 pm
If x and y are distinct positive integers, what is the value of x^4 - y^4?

[1] (y^2 + x^2) (y + x) (x - y) = 240.

[2] x^y = y^x and x > y.



[spoiler]Source: https://www.platinumgmat.com[/spoiler]
The mind is everything. What you think you become. -Lord Buddha



Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001

www.manyagroup.com
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Data Sufficiency |
User avatar
Master | Next Rank: 500 Posts
Posts: 270
Joined: Wed Apr 07, 2010 9:00 amFollowed by: 2 members
Thanked: 24 times

by neerajkumar1_1 » Sat Oct 16, 2010 12:59 am
x^4 - y^4 = (x^2-y^2)(x^2+y^2) = (y^2 + x^2) (y + x) (x - y)

statement 1) gives us exactly that...
sufficient

statement 2)

x^y = y^x x>y

now x and y cannot be 2 diff primes..

only way this is possible is
4^2 = 2^4
since x > y
x = 4 and y =2

again
sufficient..

Pick D
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 516
Joined: Mon Nov 02, 2009 6:42 amFollowed by: 1 member
Location: Mumbai
Thanked: 14 times
GMAT Score:710

by ankurmit » Sat Oct 16, 2010 1:31 am
@Neeaj ..Nice explanation about stem B
--------
Ankur mittal
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1