if X^2=y+5 , y=z-2 , z=2x Is x^3 + y^2 +z divisible by 7 a) : Quant Question Archive [LOCKED]
Check GMAT Club App Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

It is currently 07 Dec 2016, 12:37
GMAT Club Tests

Chicago-Booth

is Calling R1 Admits |  Join Chat Room2 for Live Updates


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

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

if X^2=y+5 , y=z-2 , z=2x Is x^3 + y^2 +z divisible by 7 a)

  post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Senior Manager
Senior Manager
avatar
Joined: 19 Sep 2004
Posts: 369
Followers: 1

Kudos [?]: 5 [0], given: 0

if X^2=y+5 , y=z-2 , z=2x Is x^3 + y^2 +z divisible by 7 a) [#permalink]

Show Tags

New post 02 May 2007, 16:37
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

if X^2=y+5 , y=z-2 , z=2x
Is x^3 + y^2 +z divisible by 7

a) x>0
b) y=4

Statement (1) ALONE is sufficient, but Statement (2) alone is not sufficient.
Statement (2) ALONE is sufficient, but Statement (1) alone is not sufficient.
BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
EACH statement ALONE is sufficient.
Statements (1) and (2) TOGETHER are NOT sufficient
Senior Manager
Senior Manager
User avatar
Joined: 24 Nov 2006
Posts: 350
Followers: 1

Kudos [?]: 23 [0], given: 0

Re: Real Hard one from GMAT Club Challenges [#permalink]

Show Tags

New post 02 May 2007, 16:58
x^3 + (x^2-5)^2+2x = x^4 + x^3 - 10x^2 + 2x + 25 = A

(1) For x>0 there are infinite (integer) values of the expression above. Doing some calculations we have that, for x=1, A=19; x=2, A=13; x=3, A=49. So The expression could or could not be divisible by 7. Insuff =) B, C or E.

(2) y=4 =) x=3 =) The expression is divisible by 7. Suff =) B.

One thing to point out (and that I forgot to apply in this problem) is the need to start with the easiest looking btw (1) and (2). In this case, it was (2). Doing this could surely help save some precious time on exam day.


saurabhmalpani wrote:
if X^2=y+5 , y=z-2 , z=2x
Is x^3 + y^2 +z divisible by 7

(1) x>0
(2) y=4

Statement (1) ALONE is sufficient, but Statement (2) alone is not sufficient.
Statement (2) ALONE is sufficient, but Statement (1) alone is not sufficient.
BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
EACH statement ALONE is sufficient.
Statements (1) and (2) TOGETHER are NOT sufficient
Senior Manager
Senior Manager
avatar
Joined: 19 Sep 2004
Posts: 369
Followers: 1

Kudos [?]: 5 [0], given: 0

Re: Real Hard one from GMAT Club Challenges [#permalink]

Show Tags

New post 02 May 2007, 17:17
Was a nice try but I think you forgot that only those values of X will be considered which satisfies X^2=Y+5

Thanks
Saurabh Malpani

Andr359 wrote:
x^3 + (x^2-5)^2+2x = x^4 + x^3 - 10x^2 + 2x + 25 = A

(1) For x>0 there are infinite (integer) values of the expression above. Doing some calculations we have that, for x=1, A=19; x=2, A=13; x=3, A=49. So The expression could or could not be divisible by 7. Insuff =) B, C or E.

(2) y=4 =) x=3 =) The expression is divisible by 7. Suff =) B.

One thing to point out (and that I forgot to apply in this problem) is the need to start with the easiest looking btw (1) and (2). In this case, it was (2). Doing this could surely help save some precious time on exam day.


saurabhmalpani wrote:
if X^2=y+5 , y=z-2 , z=2x
Is x^3 + y^2 +z divisible by 7

(1) x>0
(2) y=4

Statement (1) ALONE is sufficient, but Statement (2) alone is not sufficient.
Statement (2) ALONE is sufficient, but Statement (1) alone is not sufficient.
BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
EACH statement ALONE is sufficient.
Statements (1) and (2) TOGETHER are NOT sufficient
Director
Director
User avatar
Joined: 26 Feb 2006
Posts: 904
Followers: 4

Kudos [?]: 107 [0], given: 0

Re: Real Hard one from GMAT Club Challenges [#permalink]

Show Tags

New post 02 May 2007, 17:50
saurabhmalpani wrote:
if X^2 = y + 5, y = z - 2, and z = 2x,
Is x^3 + y^2 + z divisible by 7?

a) x> 0
b) y = 4


x^2 = y + 5, y = z - 2 , z = 2x
x^2 = z - 2 + 5
x^2 = 2x - 2 + 5
x^2 - 2x -3 = 0
x = -1 or 3

if x = -1, y = -4, and z = -2
if x = 3, y = 4, and z = 6


from a:
x is +ve, so x = 3.
x^3 + y^2 + z = 49. suff


from b:
y = 4 implies that x = 3.
x^3 + y^2 + z = 49. suff


So D............
Senior Manager
Senior Manager
avatar
Joined: 19 Sep 2004
Posts: 369
Followers: 1

Kudos [?]: 5 [0], given: 0

 [#permalink]

Show Tags

New post 02 May 2007, 18:01
Great Stuff. You are right on the money!!!

OA is D.

Saurabh Malpani
Senior Manager
Senior Manager
User avatar
Joined: 03 May 2007
Posts: 271
Followers: 1

Kudos [?]: 11 [0], given: 0

 [#permalink]

Show Tags

New post 03 May 2007, 07:52
To Himalayan
Thanks for explanation
It makes sense now.
Intern
Intern
avatar
Joined: 05 Jun 2003
Posts: 48
Followers: 0

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

Re: Real Hard one from GMAT Club Challenges [#permalink]

Show Tags

New post 03 May 2007, 09:35
Thanks Himalaya. You turned a difficult question into a simple and easily- understood form.
Intern
Intern
avatar
Joined: 01 Feb 2007
Posts: 17
Followers: 0

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

 [#permalink]

Show Tags

New post 03 May 2007, 16:42
Great Stuff Himalayan. Thanks
  [#permalink] 03 May 2007, 16:42
Display posts from previous: Sort by

if X^2=y+5 , y=z-2 , z=2x Is x^3 + y^2 +z divisible by 7 a)

  post reply Question banks Downloads My Bookmarks Reviews Important topics  


cron

GMAT Club MBA Forum Home| About| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.