GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 20 Oct 2019, 17:02

Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel

If x is a positive integer, which of the following must be odd?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Find Similar Topics 
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58434
If x is a positive integer, which of the following must be odd?  [#permalink]

Show Tags

New post 28 Feb 2016, 10:03
1
3
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

84% (01:05) correct 16% (01:04) wrong based on 171 sessions

HideShow timer Statistics

Manager
Manager
avatar
Joined: 25 Dec 2012
Posts: 116
Re: If x is a positive integer, which of the following must be odd?  [#permalink]

Show Tags

New post 28 Feb 2016, 10:12
Bunuel wrote:
If x is a positive integer, which of the following must be odd?

A. x+1
B. x^2+x
C. x^2+x+1
D. x^2−1
E. 3x^2−3



A. X+1 = can be odd or even. Since O + O =E or E + O = O

B. X^2 + X = X(X+1). Since from the above derivation we already know the term X+1 can be Odd or Even, directly substitute here. X(ODD) = Even (When X is Even) or X(EVEN) = EVEN [When X is ODD]

C. Here's the answer. Since we know the term x^2 + X can always take a EVEN number, EVEN + 1 = ODD

Hence C.
GMAT Club Legend
GMAT Club Legend
User avatar
V
Joined: 12 Sep 2015
Posts: 4015
Location: Canada
Re: If x is a positive integer, which of the following must be odd?  [#permalink]

Show Tags

New post 28 Feb 2016, 10:19
1
Bunuel wrote:
If x is a positive integer, which of the following must be odd?

A. x+1
B. x^2+x
C. x^2+x+1
D. x^2−1
E. 3x^2−3


Let's test some values.
Try x = 1

A. 1 + 1 = 2 EVEN - ELIMINATE A
B. 1^2 + 1 = 2 EVEN - ELIMINATE B
C. 1^2 + 1 + 1 = 3 ODD - KEEP C
D. 1^2 − 1 = 0 EVEN - ELIMINATE D
E. 3(1^2) − 3 = 0 EVEN - ELIMINATE E

Answer: C

Cheers,
Brent
_________________
Test confidently with gmatprepnow.com
Image
Senior Manager
Senior Manager
User avatar
G
Joined: 24 Nov 2015
Posts: 490
Location: United States (LA)
Reviews Badge
Re: If x is a positive integer, which of the following must be odd?  [#permalink]

Show Tags

New post 27 Mar 2016, 14:09
try 2 numbers one even and the other odd for various options to get the correct answer
Manager
Manager
avatar
S
Joined: 18 Oct 2016
Posts: 130
Location: India
WE: Engineering (Energy and Utilities)
Re: If x is a positive integer, which of the following must be odd?  [#permalink]

Show Tags

New post 13 Apr 2017, 02:12
Option C

x is a positive integer. Odd: O, Even: E & Fraction: F

x = Even or Odd = E or O

A. x + 1 = E + 1 or O + 1 = O or E
B. x^2 + x = E^2 + E or O^2 + O = E or E
C. x^2 + x + 1 = E^2 + E + 1 or O^2 + O + 1 = E + 1 or E + 1 = O or O
D. x^2 − 1 = E^2 - 1 or O^2 - 1 = E - 1 or O - 1 = O or E
E. 3x^2 − 3 = 3*E^3 - 3 or 3*O^2 - 3 = E - 3 or O - 3 = O or E
_________________
Press Kudos if you liked the post!

Rules for posting - PLEASE READ BEFORE YOU POST
GMAT Club Bot
Re: If x is a positive integer, which of the following must be odd?   [#permalink] 13 Apr 2017, 02:12
Display posts from previous: Sort by

If x is a positive integer, which of the following must be odd?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  





Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne