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

 It is currently 25 May 2015, 19:57

### 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

# m02 #13

Author Message
Manager
Joined: 10 Jul 2010
Posts: 196
Followers: 1

Kudos [?]: 18 [0], given: 12

m02 #13 [#permalink]  02 Feb 2012, 05:02
x and y are positive integers. If $$y= sqrt(64)$$ and $$x^2-10x=\frac{-4y^3+64y}{96}$$ , what is the minimum possible value of x?
A. 2
B. 4
C. 8
D. 12
E. 16

X and Y are positive integers. If $$y= sqrt(64)$$ and $$x^2-10x=\frac{-4y^3+64y}{96}$$ , what is the minimum possible value of X ?

OA is
[Reveal] Spoiler:
A

Question: How did the explanation get -3 in the numerator??

http://gmatclub.com/tests/m02#expl13

Last edited by Bunuel on 02 Feb 2012, 12:21, edited 1 time in total.
 Kaplan Promo Code Knewton GMAT Discount Codes Manhattan GMAT Discount Codes
Math Expert
Joined: 02 Sep 2009
Posts: 27494
Followers: 4312

Kudos [?]: 42311 [0], given: 6012

Re: m02 #13 [#permalink]  02 Feb 2012, 12:20
Expert's post
menacel wrote:
X and Y are positive integers. If $$y= sqrt(64)$$ and $$x^2-10x=\frac{-4y^3+64y}{96}$$ , what is the minimum possible value of X ?

OA is
[Reveal] Spoiler:
A

Question: How did the explanation get -3 in the numerator??

http://gmatclub.com/tests/m02#expl13

x and y are positive integers. If $$y= sqrt(64)$$ and $$x^2-10x=\frac{-4y^3+64y}{96}$$ , what is the minimum possible value of x?
A. 2
B. 4
C. 8
D. 12
E. 16

$$y= \sqrt{64}=8$$;

$$\frac{-4*8^3+64*8}{96}$$ --> reduce by 8*4: $$\frac{-8^2+16}{3}=\frac{-48}{3}=-16$$ (the way they got 3 in nominator: $$-4*8^3+8^3=1*8^3-4*8^3=-3*8^3$$);

Next, $$x^2-10x=-16$$ --> $$x=2$$ or $$x=8$$. Hence, the minimum possible value of x is 2.

Hope it's clear.
_________________
Manager
Joined: 10 Jul 2010
Posts: 196
Followers: 1

Kudos [?]: 18 [0], given: 12

Re: m02 #13 [#permalink]  03 Feb 2012, 06:28
Bunuel wrote:
menacel wrote:
X and Y are positive integers. If $$y= sqrt(64)$$ and $$x^2-10x=\frac{-4y^3+64y}{96}$$ , what is the minimum possible value of X ?

OA is
[Reveal] Spoiler:
A

Question: How did the explanation get -3 in the numerator??

http://gmatclub.com/tests/m02#expl13

x and y are positive integers. If $$y= sqrt(64)$$ and $$x^2-10x=\frac{-4y^3+64y}{96}$$ , what is the minimum possible value of x?
A. 2
B. 4
C. 8
D. 12
E. 16

$$y= \sqrt{64}=8$$;

$$\frac{-4*8^3+64*8}{96}$$ --> reduce by 8*4: $$\frac{-8^2+16}{3}=\frac{-48}{3}=-16$$ (the way they got 3 in nominator: $$-4*8^3+8^3=1*8^3-4*8^3=-3*8^3$$);

Next, $$x^2-10x=-16$$ --> $$x=2$$ or $$x=8$$. Hence, the minimum possible value of x is 2.

Hope it's clear.

much clearer thanks a lot!
Re: m02 #13   [#permalink] 03 Feb 2012, 06:28
Similar topics Replies Last post
Similar
Topics:
3 M02-13 5 15 Sep 2014, 23:17
15 m02 #21 28 14 Nov 2008, 12:33
40 m02#24 14 05 Nov 2008, 07:21
21 m02#8 16 03 Nov 2008, 15:24
1 Factoring...? (m02 #8) 5 27 Feb 2008, 21:50
Display posts from previous: Sort by

# m02 #13

Moderators: Bunuel, WoundedTiger

 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®.