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

It is currently 30 Jun 2015, 06:59

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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

If xy = -6 , what is the value of xy(x+y ) ? (1) x y = 5 (2)

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Manager
Manager
avatar
Joined: 30 Jun 2006
Posts: 87
Followers: 0

Kudos [?]: 4 [0], given: 0

If xy = -6 , what is the value of xy(x+y ) ? (1) x y = 5 (2) [#permalink] New post 18 Apr 2007, 10:00
If xy = -6 , what is the value of xy(x+y ) ?
(1) x – y = 5
(2) xy^2 = 18

My answer doesn't match with the answer given. Would like to know your answers.

Thanks
Senior Manager
Senior Manager
avatar
Joined: 23 Jun 2006
Posts: 387
Followers: 1

Kudos [?]: 311 [0], given: 0

 [#permalink] New post 18 Apr 2007, 10:52
answer is B

st2 is sufficient:
xy^2=18 = xy*y = (-6)*y hence y must be -3 from which you can go forward and get the value of xy(x+y)

st1: is insufficient
x-y=5 (together with xy=-6) has two solutions: x=2 y=-3 and x=3 y=-2 which lead to diferent answers - hence insufficient
VP
VP
User avatar
Joined: 08 Jun 2005
Posts: 1146
Followers: 6

Kudos [?]: 136 [0], given: 0

 [#permalink] New post 18 Apr 2007, 10:56
My answer is (B)

I can see that hobbit gave a full and detailed explanation so I will not explain again (same logic) - well done hobbit :-D
Manager
Manager
avatar
Joined: 09 Sep 2004
Posts: 165
Followers: 1

Kudos [?]: 1 [0], given: 0

 [#permalink] New post 18 Apr 2007, 13:55
I agree with hobbit B.
Senior Manager
Senior Manager
avatar
Joined: 11 Feb 2007
Posts: 356
Followers: 1

Kudos [?]: 47 [0], given: 0

 [#permalink] New post 18 Apr 2007, 19:01
B indeed! :)

xy^2=18
18=2*3^2

thus x=2 y=-3

Suff~
GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 07 Jul 2004
Posts: 5068
Location: Singapore
Followers: 23

Kudos [?]: 192 [0], given: 0

 [#permalink] New post 18 Apr 2007, 19:24
St1:
x = y+5
So
y(y+5) = -6
y^2 +5y + 6 = 0
y = -2 or y = -3

If y = -2, x = 3 --> xy(x+y) = -6
If y = -3, x = 2 --> xy(x+y) = -30

Insufficient.

St2:
xy^2 = 18
x = 18/y^2

So
(18/y^2)(y) = 6
18/y = 6
y = 3.

So x = 2. One (x,y) pair will give only one result for xy(x+y).

sufficient.

Ans B
Manager
Manager
avatar
Joined: 28 Feb 2007
Posts: 197
Location: California
Followers: 2

Kudos [?]: 6 [0], given: 0

Re: Conflicting answers [#permalink] New post 18 Apr 2007, 19:55
jainvik7 wrote:
If xy = -6 , what is the value of xy(x+y ) ?
(1) x – y = 5
(2) xy^2 = 18

My answer doesn't match with the answer given. Would like to know your answers.

Thanks


B.

x-y=5 gives 2 sets of solutions
while xy^2=18 gives only 1
Re: Conflicting answers   [#permalink] 18 Apr 2007, 19:55
    Similar topics Author Replies Last post
Similar
Topics:
For integers and x ,y x=y/6+1 . Is xy even? 1. y+1/5 = x 2 jackychamp 2 17 Nov 2008, 20:27
1 If 6xy = (x^2)y + 9y, what is the value of xy? (1) y - x = 3 brokerbevo 4 04 Aug 2008, 10:19
1 If 6xy = x^2y + 9y, what is the value of xy? (1) y x = 3 (2) stingraybullray 15 16 Jul 2008, 05:21
If x=3/4 and y=1/5, what is the value of sqrt(x^2 + 6x + 9) ajay_gmat 10 25 Jul 2007, 03:18
If x=3/4 and y=1/5, what is the value of sqrt(x^2 + 6x + 9) ajay_gmat 13 24 Jul 2007, 21:46
Display posts from previous: Sort by

If xy = -6 , what is the value of xy(x+y ) ? (1) x y = 5 (2)

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| 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®.