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 →

OG math.

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
Master | Next Rank: 500 Posts
Posts: 277
Joined: Sun Jun 17, 2007 2:51 pmFollowed by: 1 member
Location: New York, NY
Thanked: 6 times
by givemeanid » Mon Sep 03, 2007 12:58 pm
'could be' is the key. Question is not asking which value will 'always be' a prime. Check other choices and you will realize there is no value of X for which the other choices will ever be true.
So It Goes
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
Master | Next Rank: 500 Posts
Posts: 140
Joined: Sat Feb 28, 2009 8:51 amFollowed by: 3 members
Location: India
Thanked: 14 times

Re: OG math.

by farooq » Fri Oct 30, 2009 7:54 am
aditya33 wrote:If X is a prime number greater than 2.Which of the following could be a prime number??

1-X^2
2-X/2
3-3X
4-X-4
5-X^2+1..

Ans is:- d (X-4)..But if i choose 13 as a prime number then it could be 13-4=9 which is not a prime numeber.Although 11-4=7 which is a prime no.So,this ans gives us two different answers..I am confused which one should be correct..
Plss help.
If X is a prime number greater than 2.Which of the following could be a prime number??

It means is there any choice that can be a prime no. for X.

Only option D full fill this possibility.
Regards,
Farooq Farooqui.
London. UK

It is your Attitude, not your Aptitude, that determines your Altitude.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Senior | Next Rank: 100 Posts
Posts: 70
Joined: Mon Oct 05, 2009 9:33 am

Re: OG math.

by chipbmk » Fri Oct 30, 2009 10:02 am
aditya33 wrote:If X is a prime number greater than 2.Which of the following could be a prime number??

1-X^2
2-X/2
3-3X
4-X-4
5-X^2+1..

Ans is:- d (X-4)..But if i choose 13 as a prime number then it could be 13-4=9 which is not a prime numeber.Although 11-4=7 which is a prime no.So,this ans gives us two different answers..I am confused which one should be correct..
Plss help.
Although the other posters seem to have answered your question, I thought I could provide slightly more detail.

1- x^2 can't be a prime because it will be divisible by 1, x^2, and x.
2- x/2 can't be prime because x is odd and an odd divided by 2 is not an integer
3- 3x can't be prime because it will have 1, x, and 3 as factors.
4- you proved this one yourself
5- x^2+1 can't be prime because if x is odd (as question says it is) than once you add 1 it will be an even. No even greater than 2 is a prime.

Hope that was helpful.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1