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.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 350,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

Cheers! JT........... If u like my post..... payback in Kudos!!

|Do not post questions with OA|Please underline your SC questions while posting|Try posting the explanation along with your answer choice| |For CR refer Powerscore CR Bible|For SC refer Manhattan SC Guide|

~~Better Burn Out... Than Fade Away~~

Last edited by Bunuel on 07 Jan 2014, 06:13, edited 3 times in total.

Re: Is integer x prime? [#permalink]
07 Mar 2010, 10:02

kp1811 wrote:

jeeteshsingh wrote:

Is Integer x prime? 1. x^2-3 is an even number 2. x+2 is an odd number

Please explain

E...

Made the question more clear for you...! _________________

Cheers! JT........... If u like my post..... payback in Kudos!!

|Do not post questions with OA|Please underline your SC questions while posting|Try posting the explanation along with your answer choice| |For CR refer Powerscore CR Bible|For SC refer Manhattan SC Guide|

Re: Is integer x prime? [#permalink]
07 Mar 2010, 10:26

kp1811 wrote:

jeeteshsingh wrote:

will try to make it more clearer.....

stmnt1) x^2 - 3 is even

let x = 3 (prime) then 3^2 - 3 = 6 even let x =9 (non prime) then 9^2 - 3 = 78 even hence insuff

stmnt2) x+2 is odd let x = 3 (prime) then 3 + 2 = 5 odd let x =9 (non prime) then 9 + 2 = 11 odd hence insuff

even together they don't suffice. Hence E

Some how I dont get this approach as you use the ques to prove the statement below. This question is from PR 1012 and I see the same solution there which isnt convincing for me.

My approach is as follows:

Given x is an integer. Ques is x prime?

S1: x^2 - 3 = even x^2 - 3 = 2m where m is an integer x = sqrt(2m + 3) where m is >= 0 as you cannot have - ve sqrt.

This gives x = \sqrt{3},\sqrt{5},\sqrt{7},3,\sqrt{11},\sqrt{13},\sqrt{15},\sqrt{17},\sqrt{19},\sqrt{21},\sqrt{23},5,\sqrt{27},\sqrt{29},..... Since it is given that x is an integer we get only 3, 5, 7..... which are all prime. Hence SUFF.

S2: x + 2 is odd x + 2 = 2k + 1 where k is an integer x = 2k - 1 Therefore x = ....-7,-5,-3,-1,1,3,5,7,9,11... which means all odd numbers and hence not necessarily be prime. Therefore NOT SUFF.

Hence answer is A....!

Can someone highlight what is wrong in my approach! _________________

Cheers! JT........... If u like my post..... payback in Kudos!!

|Do not post questions with OA|Please underline your SC questions while posting|Try posting the explanation along with your answer choice| |For CR refer Powerscore CR Bible|For SC refer Manhattan SC Guide|

Re: Is integer x prime? [#permalink]
07 Mar 2010, 10:34

2

This post received KUDOS

jeeteshsingh wrote:

kp1811 wrote:

jeeteshsingh wrote:

will try to make it more clearer.....

stmnt1) x^2 - 3 is even

let x = 3 (prime) then 3^2 - 3 = 6 even let x =9 (non prime) then 9^2 - 3 = 78 even hence insuff

stmnt2) x+2 is odd let x = 3 (prime) then 3 + 2 = 5 odd let x =9 (non prime) then 9 + 2 = 11 odd hence insuff

even together they don't suffice. Hence E

Some how I dont get this approach as you use the ques to prove the statement below. This question is from PR 1012 and I see the same solution there which isnt convincing for me.

My approach is as follows:

Given x is an integer. Ques is x prime?

S1: x^2 - 3 = even x^2 - 3 = 2m where m is an integer x = sqrt(2m + 3) where m is >= 0 as you cannot have - ve sqrt.

This gives x = \sqrt{3},\sqrt{5},\sqrt{7},3,\sqrt{11},\sqrt{13},\sqrt{15},\sqrt{17},\sqrt{19},\sqrt{21},\sqrt{23},5,\sqrt{27},\sqrt{29},..... Since it is given that x is an integer we get only 3, 5, 7..... which are all prime. Hence SUFF.

S2: x + 2 is odd x + 2 = 2k + 1 where k is an integer x = 2k - 1 Therefore x = ....-7,-5,-3,-1,1,3,5,7,9,11... which means all odd numbers and hence not necessarily be prime. Therefore NOT SUFF.

Hence answer is A....!

Can someone highlight what is wrong in my approach!

in highlighted part after 3,5, 7 .... 9 will come [ for m = 39] which is non prime

Re: Is integer x prime? [#permalink]
07 Mar 2010, 10:39

kp1811 wrote:

jeeteshsingh wrote:

Some how I dont get this approach as you use the ques to prove the statement below. This question is from PR 1012 and I see the same solution there which isnt convincing for me.

My approach is as follows:

Given x is an integer. Ques is x prime?

S1: x^2 - 3 = even x^2 - 3 = 2m where m is an integer x = sqrt(2m + 3) where m is >= 0 as you cannot have - ve sqrt.

This gives x = \sqrt{3},\sqrt{5},\sqrt{7},3,\sqrt{11},\sqrt{13},\sqrt{15},\sqrt{17},\sqrt{19},\sqrt{21},\sqrt{23},5,\sqrt{27},\sqrt{29},..... Since it is given that x is an integer we get only 3, 5, 7..... which are all prime. Hence SUFF.

S2: x + 2 is odd x + 2 = 2k + 1 where k is an integer x = 2k - 1 Therefore x = ....-7,-5,-3,-1,1,3,5,7,9,11... which means all odd numbers and hence not necessarily be prime. Therefore NOT SUFF.

Hence answer is A....!

Can someone highlight what is wrong in my approach!

in highlighted part after 3,5, 7 .... 9 will come [ for m = 39] which is non prime

Thanks mate! Got it Now! Kudos +1 _________________

Cheers! JT........... If u like my post..... payback in Kudos!!

|Do not post questions with OA|Please underline your SC questions while posting|Try posting the explanation along with your answer choice| |For CR refer Powerscore CR Bible|For SC refer Manhattan SC Guide|

Re: Is integer x prime? [#permalink]
07 Jan 2014, 23:16

jeeteshsingh wrote:

kp1811 wrote:

jeeteshsingh wrote:

will try to make it more clearer.....

stmnt1) x^2 - 3 is even

let x = 3 (prime) then 3^2 - 3 = 6 even let x =9 (non prime) then 9^2 - 3 = 78 even hence insuff

stmnt2) x+2 is odd let x = 3 (prime) then 3 + 2 = 5 odd let x =9 (non prime) then 9 + 2 = 11 odd hence insuff

even together they don't suffice. Hence E

Some how I dont get this approach as you use the ques to prove the statement below. This question is from PR 1012 and I see the same solution there which isnt convincing for me.

My approach is as follows:

Given x is an integer. Ques is x prime?

S1: x^2 - 3 = even x^2 - 3 = 2m where m is an integer x = sqrt(2m + 3) where m is >= 0 as you cannot have - ve sqrt.

This gives x = \sqrt{3},\sqrt{5},\sqrt{7},3,\sqrt{11},\sqrt{13},\sqrt{15},\sqrt{17},\sqrt{19},\sqrt{21},\sqrt{23},5,\sqrt{27},\sqrt{29},..... Since it is given that x is an integer we get only 3, 5, 7..... which are all prime. Hence SUFF.

S2: x + 2 is odd x + 2 = 2k + 1 where k is an integer x = 2k - 1 Therefore x = ....-7,-5,-3,-1,1,3,5,7,9,11... which means all odd numbers and hence not necessarily be prime. Therefore NOT SUFF.

Hence answer is A....!

Can someone highlight what is wrong in my approach!

Hello, Just a small thing You say "x = sqrt(2m + 3) where m is >= 0 as you cannot have - ve sqrt." but your m can be -1, still square root would be +ve i.e 1; now you have to add x=1 to your list :1,3,5,7 etc. As 1 is not prime. A becomes insufficient.

Re: Is integer x prime? [#permalink]
02 Feb 2014, 02:16

Stmt 1: x^2-3 is even simply means x is odd integer. Now x being odd is not sufficient for it to be prime. INSUFF Stm2: x+2 is odd means x is odd integer. Therefore stmt 1 & 2 are same. INSUFF

Both statements together give no new information. hence E. _________________

Click on Kudos if you liked the post!

Practice makes Perfect.

gmatclubot

Re: Is integer x prime?
[#permalink]
02 Feb 2014, 02:16

hey guys, A metallurgist but currently working in a NGO and have scheduled my GMAT in December for second round .....u know. I read some but valuable blogs on this...

Today, 1st year Rotman students had a great simulation event hosted by Scotiabank, one of Canada’s best and largest banks. Attended by entire Rotman 1st year students, the...

Nope. I never learned finance ever in my life until I came to Rotman. This is why I got really frustrated when this term started because I was certain...