Check GMAT Club Decision Tracker for the Latest School Decision Releases https://gmatclub.com/AppTrack

 It is currently 25 May 2017, 09:45

### 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

# Given that xy > 0, which of the following must also be

Author Message
TAGS:

### Hide Tags

Magoosh GMAT Instructor
Joined: 28 Dec 2011
Posts: 4035
Followers: 1416

Kudos [?]: 6768 [1] , given: 84

Given that xy > 0, which of the following must also be [#permalink]

### Show Tags

09 Jul 2013, 10:23
1
KUDOS
Expert's post
1
This post was
BOOKMARKED
00:00

Difficulty:

5% (low)

Question Stats:

85% (01:38) correct 15% (00:43) wrong based on 179 sessions

### HideShow timer Statistics

Given that xy > 0, which of the following must also be greater than zero?

(A) $$x + y$$
(B) $$x^2 + y$$
(C) $$(x + y)^2$$
(D) $$x^2 - y^2 + 100$$
(E) $$(x - y)^2$$

For a discussion of plugging in numbers, as well as a full solution to this question, see:
http://magoosh.com/gmat/2013/how-to-plu ... questions/

Mike
[Reveal] Spoiler: OA

_________________

Mike McGarry
Magoosh Test Prep

 Magoosh Discount Codes Veritas Prep GMAT Discount Codes Optimus Prep Discount Codes
Director
Status: Done with formalities.. and back..
Joined: 15 Sep 2012
Posts: 641
Location: India
Concentration: Strategy, General Management
Schools: Olin - Wash U - Class of 2015
WE: Information Technology (Computer Software)
Followers: 49

Kudos [?]: 589 [0], given: 23

Re: Given that xy > 0, which of the following must also be [#permalink]

### Show Tags

09 Jul 2013, 10:49
mikemcgarry wrote:
Given that xy > 0, which of the following must also be greater than zero?

(A) $$x + y$$
(B) $$x^2 + y$$
(C) $$(x + y)^2$$
(D) $$x^2 - y^2 + 100$$
(E) $$(x - y)^2$$

For a discussion of plugging in numbers, as well as a full solution to this question, see:
http://magoosh.com/gmat/2013/how-to-plu ... questions/

Mike

Actually if u just go through the options.. you'll notice that option C, is a perfect square.. which has to be greater than or equal to zero. Now looking back at the question, we know xy>0, which implies x and y are not equal to 0 and are of same sign. therefore x+y will be a non zero number and its square would be greater than 0.

Ans C it is.
_________________

Lets Kudos!!!
Black Friday Debrief

GMAT Club Legend
Joined: 09 Sep 2013
Posts: 15439
Followers: 649

Kudos [?]: 209 [0], given: 0

Re: Given that xy > 0, which of the following must also be [#permalink]

### Show Tags

11 Apr 2015, 19:13
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
Director
Joined: 05 Mar 2015
Posts: 905
Followers: 9

Kudos [?]: 198 [0], given: 40

Re: Given that xy > 0, which of the following must also be [#permalink]

### Show Tags

25 Dec 2015, 07:33
[quote="mikemcgarry"]Given that xy > 0, which of the following must also be greater than zero?

(A) $$x + y$$
(B) $$x^2 + y$$
(C) $$(x + y)^2$$
(D) $$x^2 - y^2 + 100$$
(E) $$(x - y)^2$$

We are not told that X & Y were integers.
Consider X=Y=1/2

only option C fits in.....
Magoosh GMAT Instructor
Joined: 28 Dec 2011
Posts: 4035
Followers: 1416

Kudos [?]: 6768 [0], given: 84

Re: Given that xy > 0, which of the following must also be [#permalink]

### Show Tags

25 Dec 2015, 09:25
rohit8865 wrote:
mikemcgarry wrote:
Given that xy > 0, which of the following must also be greater than zero?

(A) $$x + y$$
(B) $$x^2 + y$$
(C) $$(x + y)^2$$
(D) $$x^2 - y^2 + 100$$
(E) $$(x - y)^2$$

We are not told that X & Y were integers.
Consider X=Y=1/2

only option C fits in.....

Dear rohit8865,
Quite true, my friend: the values of x & y are not necessarily integers and not necessarily positive. The two perfect squares, (C) & (E), must be greater than or equal to zero. As you figured out, if the two variables are equal non-zero numbers (whether positive or negative), then (E) will equal zero and not work. Only (C) works.
Good job!
Mike
_________________

Mike McGarry
Magoosh Test Prep

Re: Given that xy > 0, which of the following must also be   [#permalink] 25 Dec 2015, 09:25
Similar topics Replies Last post
Similar
Topics:
If xy>0, which of the following must be positive? 8 21 May 2017, 01:44
1 If xy>0, which of the following must be positive? 2 16 Apr 2017, 18:30
2 If x/y is an integer, which of the following must also be an integer? 4 03 Mar 2016, 18:42
37 If xy > 0 and yz < 0, which of the following must be negativ 15 16 Apr 2017, 06:35
25 If xy > 0 and yz < 0, which of the following must be negativ 12 12 May 2017, 03:20
Display posts from previous: Sort by