|
Author |
Message |
|
TAGS:
|
|
|
Intern
Joined: 15 Sep 2011
Posts: 17
Followers: 0
Kudos [?]:
0
[0], given: 6
|
If xy = – 6, what is the value of xy(x + y)? (1) x – y = 5 [#permalink]
 27 Apr 2012, 10:39
Question Stats:
42% (02:08) correct
57% (00:57) wrong based on 4 sessions
If xy = – 6, what is the value of xy(x + y)? (1) x – y = 5 (2) xy^2= 18
Last edited by Bunuel on 27 Apr 2012, 10:43, edited 1 time in total.
Edited the question and added the OA
|
|
|
|
|
|
|
GMAT Club team member
Joined: 02 Sep 2009
Posts: 11628
Followers: 1802
Kudos [?]:
9611
[1] , given: 829
|
Re: If xy = – 6, what is the value of xy(x + y)? (1) x – y = 5 [#permalink]
27 Apr 2012, 10:48
1
This post received
KUDOS
|
|
|
|
|
|
Intern
Joined: 15 Sep 2011
Posts: 17
Followers: 0
Kudos [?]:
0
[0], given: 6
|
Re: If xy = – 6, what is the value of xy(x + y)? (1) x – y = 5 [#permalink]
27 Apr 2012, 10:52
Bunuel wrote: If xy = – 6, what is the value of xy(x + y)?
(1) x-y=5 --> x=y+5 --> xy=(y+5)y=-6 --> y^2+5y+6=0 --> y=-3 or y=-2. If y=-3 then x=y+5=2 so xy(x+y)=-6(x+y)=6. But if y=-2 then x=y+5=3 so xy(x+y)=-6(x+y)=-6. Two different answers, hence not sufficient.
(2) x*y^2=18 --> xy*y=-6*y=18 --> y=-3 --> x=2 --> xy(x+y)=-6(x+y)=6. Sufficient.
Answer: B. B is OA, thank you!!!
|
|
|
|
|
|
Manager
Joined: 21 Aug 2012
Posts: 117
Followers: 0
Kudos [?]:
4
[0], given: 5
|
If xy = -6 , what is the value of xy(x+y ) [#permalink]
14 Feb 2013, 09:18
If xy = -6 , what is the value of xy(x+y ) ?
(1) x – y = 5
(2)xy^2 = 48
|
|
|
|
|
|
Manager
Status: Fondling the GMAT
Joined: 22 Feb 2012
Posts: 184
Location: India
Concentration: Finance, International Business
GMAT Date: 06-20-2013
GPA: 2.34
WE: Business Development (Manufacturing)
Followers: 15
Kudos [?]:
103
[0], given: 76
|
Re: If xy = -6 , what is the value of xy(x+y ) [#permalink]
14 Feb 2013, 09:39
roopika2990 wrote: If xy = -6 , what is the value of xy(x+y ) ?
(1) x – y = 5
(2)xy^2 = 48 xy=-6 ----> x=-6/y S1) x-y=5 ---------------> x=y+5 -------------> -6/y=y+5 --------> y^2 + 5y + 6 = 0 -------> y = -3 or -2 two values for y so not sufficiesnt S2) xy^2 = 48 -------> We know x=-6/y -------> therefore (-6/y)(y^2)=48 -------> -6y = 48 -------> y = -8 and x = 6/8 so now we can calculate the value of xy(x+y) hence statement is sufficient Regards, Abhijit
_________________
Please Read this before Posting your question rules-for-posting-in-verbal-gmat-forum-134642.html#p1097623
When it rains, All birds occupy shelters. But Eagle is the only bird that avoids the rain by flying above the clouds.
Problems common to all. Attitude makes the difference
Concept Initiator Articles
co-ordinate-geometry-simplified-149570.html
time-speed-and-distance-simplified-150163.html
permutations-and-combinations-simplified-150835.html
NEW!!UPCOMING in Simplification Series - INEQUATIONS (Inequalities).
|
|
|
|
|
|
Senior Manager
Joined: 10 Oct 2012
Posts: 287
Followers: 4
Kudos [?]:
94
[0], given: 20
|
Re: If xy = -6 , what is the value of xy(x+y ) [#permalink]
14 Feb 2013, 11:36
(x+y)^2 = (x-y)^2+4xy
= 5^2+4(-6) = 25-24 = 1
From F.S 1, we know that (x+y)^2 will have two values 1 and -1. Hence, insufficient.
But, from F.S 2, we know that y will have only one value. Thus sufficient. No need to solve for either of the options.
B.
|
|
|
|
|
|
GMAT Club team member
Joined: 02 Sep 2009
Posts: 11628
Followers: 1802
Kudos [?]:
9611
[0], given: 829
|
Re: If xy = -6 , what is the value of xy(x+y ) [#permalink]
14 Feb 2013, 15:24
|
|
|
|
|
|
|
Re: If xy = -6 , what is the value of xy(x+y )
[#permalink]
14 Feb 2013, 15:24
|
|
|
|
|
|
|
|
|
|
|
close
