Is x^2 equal to xy? : GMAT Data Sufficiency (DS)
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 22 Jan 2017, 18:46

### 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

# Is x^2 equal to xy?

Author Message
TAGS:

### Hide Tags

Director
Joined: 05 Jan 2008
Posts: 701
Followers: 5

Kudos [?]: 417 [0], given: 0

Is x^2 equal to xy? [#permalink]

### Show Tags

20 May 2008, 23:44
3
This post was
BOOKMARKED
00:00

Difficulty:

35% (medium)

Question Stats:

64% (02:15) correct 36% (01:08) wrong based on 170 sessions

### HideShow timer Statistics

Is x^2 equal to xy?

(1) x^2 – y^2 = (x + 5)(y - 5)
(2) x = y

OPEN DISCUSSION OF THIS QUESTION IS HERE: is-x-2-equal-to-xy-88034.html
[Reveal] Spoiler: OA

_________________

Persistence+Patience+Persistence+Patience=G...O...A...L

Last edited by Bunuel on 28 Oct 2014, 03:10, edited 2 times in total.
Edited the question and added the OA.
Director
Joined: 14 Aug 2007
Posts: 733
Followers: 10

Kudos [?]: 182 [0], given: 0

Re: Is x^2 equal to xy? [#permalink]

### Show Tags

20 May 2008, 23:57
prasannar wrote:
Is x^2 equal to xy?
(1) x2 – y2 = (x + 5)(y - 5)
(2) x = y

D,

1) Assuming x2 - y2 is a typo for x^2-y^2,

(x+y)(x-y) = (-5 + y) (x - (-5) )
i.e. x =-5 & y = -5

2) is suff
SVP
Joined: 04 May 2006
Posts: 1926
Schools: CBS, Kellogg
Followers: 23

Kudos [?]: 1013 [0], given: 1

Re: Is x^2 equal to xy? [#permalink]

### Show Tags

21 May 2008, 00:01
alpha_plus_gamma wrote:
(x+y)(x-y) = (-5 + y) (x - (-5) )
i.e. x =-5 & y = -5

you seem right!
_________________
Director
Joined: 05 Jan 2008
Posts: 701
Followers: 5

Kudos [?]: 417 [0], given: 0

Re: Is x^2 equal to xy? [#permalink]

### Show Tags

21 May 2008, 01:49
Given OA is B.

I too picked D and got nailed down by the OA.

Patman how did you get to B, plz explain
_________________

Persistence+Patience+Persistence+Patience=G...O...A...L

VP
Joined: 18 May 2008
Posts: 1286
Followers: 16

Kudos [?]: 411 [0], given: 0

Re: Is x^2 equal to xy? [#permalink]

### Show Tags

21 May 2008, 03:34
(1)x^2-y^2=(x+y)(x-y)=(x + 5)(y - 5)
so y=5 but no information abt x so insufficient

(2) x=y
multiplying both sides by x
x^2=xy sufficient
Current Student
Joined: 28 Dec 2004
Posts: 3384
Location: New York City
Schools: Wharton'11 HBS'12
Followers: 15

Kudos [?]: 282 [0], given: 2

Re: Is x^2 equal to xy? [#permalink]

### Show Tags

21 May 2008, 05:52
this should be B..

x^2-y^2=(x-y)(x+y)..

we have (x+5)(y-5)... (y-5) is not equal to (x-y)

here x is negative...so insuff
Intern
Joined: 18 Dec 2013
Posts: 40
GPA: 2.84
WE: Project Management (Telecommunications)
Followers: 0

Kudos [?]: 24 [0], given: 98

Re: Is x^2 equal to xy? [#permalink]

### Show Tags

27 Oct 2014, 18:43
prasannar wrote:
Is x^2 equal to xy?
(1) x2 – y2 = (x + 5)(y - 5)
(2) x = y

ritula wrote:
(1)x^2-y^2=(x+y)(x-y)=(x + 5)(y - 5)
so y=5 but no information abt x so insufficient

(2) x=y
multiplying both sides by x
x^2=xy sufficient

FN wrote:
this should be B..

x^2-y^2=(x-y)(x+y)..

we have (x+5)(y-5)... (y-5) is not equal to (x-y)

here x is negative...so insuff

Can someone please explain this DS problem in more detail?
Bunuel ??... Please can you help! TY
Math Expert
Joined: 02 Sep 2009
Posts: 36601
Followers: 7097

Kudos [?]: 93479 [1] , given: 10563

Re: Is x^2 equal to xy? [#permalink]

### Show Tags

28 Oct 2014, 03:07
1
KUDOS
Expert's post
2
This post was
BOOKMARKED
dmmk wrote:
prasannar wrote:
Is x^2 equal to xy?
(1) x2 – y2 = (x + 5)(y - 5)
(2) x = y

ritula wrote:
(1)x^2-y^2=(x+y)(x-y)=(x + 5)(y - 5)
so y=5 but no information abt x so insufficient

(2) x=y
multiplying both sides by x
x^2=xy sufficient

FN wrote:
this should be B..

x^2-y^2=(x-y)(x+y)..

we have (x+5)(y-5)... (y-5) is not equal to (x-y)

here x is negative...so insuff

Can someone please explain this DS problem in more detail?
Bunuel ??... Please can you help! TY

Is x^2 equal to xy?

Question: is $$x^2=xy$$? --> $$x(x-y)=0$$ --> Equation holds true if $$x=0$$ or/and $$x=y$$.

So, basically question asks: Is $$x=0$$ or/and $$x=y$$ true?

Obviously statement (2) is sufficient, as it gives directly that $$x=y$$.

(1) x^2 – y^2 = (x + 5)(y - 5) --> $$(x+y)(x-y)=(x + 5)(y-5)$$

If $$y=5$$ --> $$(x+5)(x-5)=(x+5)(5-5)$$ --> $$(x+5)(x-5)=0$$ --> Either $$x=5=y$$ and in this case answer to the question is YES OR $$x=-5$$, hence $$x$$ is not equal to $$y$$ (nor to zero) and in this case answer to the question is NO. So two different answers.

Not sufficient.

OPEN DISCUSSION OF THIS QUESTION IS HERE: is-x-2-equal-to-xy-88034.html
_________________
Re: Is x^2 equal to xy?   [#permalink] 28 Oct 2014, 03:07
Similar topics Replies Last post
Similar
Topics:
4 If 4t/3x = 2/3y + 2/5y and xy is not equal to 0, is t equal to 1? 4 04 Apr 2016, 06:13
5 Is x^2 equal to xy? 6 06 Oct 2015, 04:50
2 If xy is not equal to 0, what is the value of 25x^2/y^2? (1) 7 28 Oct 2010, 21:30
5 If xy does not equal 0, what is the value of ((x^2)^3 y^4)/x 7 19 Oct 2010, 11:15
7 Is x^2 equal to xy? 9 15 Dec 2009, 22:28
Display posts from previous: Sort by