Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 03 Jul 2015, 21:07

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# Does p^2 = q if p is a prime number?

Author Message
TAGS:
Intern
Joined: 11 Sep 2011
Posts: 26
Followers: 1

Kudos [?]: 16 [0], given: 0

Does p^2 = q if p is a prime number? [#permalink]  08 Apr 2012, 13:08
2
This post was
BOOKMARKED
00:00

Difficulty:

75% (hard)

Question Stats:

55% (02:03) correct 45% (02:07) wrong based on 98 sessions
Does p^2 = q if p is a prime number?

(1) q^2 - p^2 = 0
(2) p^2 = 49

I did not understand the OA.

From (1) - if p = 1, then q^2 = p^2 = p = +/-q
if p = 2, then p^2 = 4,p^2 is not equal to p. So (1) is not sufficient.
[Reveal] Spoiler: OA
Math Expert
Joined: 02 Sep 2009
Posts: 28272
Followers: 4469

Kudos [?]: 45137 [0], given: 6645

Re: Does p^2 = q if p is a prime number? [#permalink]  08 Apr 2012, 13:22
Expert's post
Does p^2 = q if p is a prime number?

Notice that we are told that p is a prime number.

(1) q^2 - p^2 = 0 --> $$p^2=q^2$$. Now, if $$p^2 = q$$ is true, then from $$p^2=q^2$$ we would have that $$q=q^2$$ --> $$q(q-1)=0$$ --> $$q=0$$ or $$q=1$$, but in this case $$p$$ becomes -1, 0, or 1, none of which is a prime number. Hence, $$p^2\neq{q}$$. Sufficient.

(2) p^2 = 49. Not sufficient as no info about $$q$$.

Hope it's clear.
_________________
Manager
Joined: 12 Feb 2012
Posts: 108
Followers: 1

Kudos [?]: 19 [0], given: 28

Re: Does p^2 = q if p is a prime number? [#permalink]  14 Apr 2012, 10:29
I got this question wrong only because I thought the number 1 was prime, in that case A would have been insuffient. Let this be a lesson to you all. The number 1 is neither a prime nor a composite!!
Math Expert
Joined: 02 Sep 2009
Posts: 28272
Followers: 4469

Kudos [?]: 45137 [0], given: 6645

Re: Does p^2 = q if p is a prime number? [#permalink]  29 May 2013, 06:26
Expert's post
Bumping for review and further discussion.
_________________
Manager
Joined: 21 Oct 2013
Posts: 194
Location: Germany
GMAT 1: 660 Q45 V36
GPA: 3.51
Followers: 0

Kudos [?]: 22 [0], given: 19

Does p^2 = q if p is a prime number? [#permalink]  08 Jul 2014, 02:44
I approached this question as a YES/NO question.

Q: is p²=q? p is PRIME.

(1) q²-p²=0 , hence q²=p². This can only happen if q=1, -1 or 0, hence p also 1 or 0 which is no prime. Answer is NO, hence Suff.
(2) gives us no info about q, so IS.

Does p^2 = q if p is a prime number?   [#permalink] 08 Jul 2014, 02:44
Similar topics Replies Last post
Similar
Topics:
2 Given that (P + 2Q) is a positive number, what is the value of (P + 2Q 5 05 Mar 2015, 08:53
Does P^2 = Q if P is a prime number? (1) Q^2 - P^2 = 0 (2) 1 12 Mar 2008, 07:59
Is prime number p equal to 37 ? 1. p=n^2+1 2. p^2 > 200 2 22 Nov 2007, 17:01
Does p^2 = q if p is a prime number? (1) q^2 - p^2 = 0 (2) 8 20 Nov 2005, 20:46
Does p^2=q if p is a prime number? 1. q^2-p^2=0 2. p^2=49 6 24 Jul 2005, 06:04
Display posts from previous: Sort by