It is currently 17 Oct 2017, 02:54

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.

Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

If xyz ≠ 0, is x(y + z) = 0?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Senior Manager
Senior Manager
User avatar
Joined: 03 Mar 2010
Posts: 422

Kudos [?]: 360 [0], given: 22

Schools: Simon '16 (M)
If xyz ≠ 0, is x(y + z) = 0? [#permalink]

Show Tags

New post 21 Jun 2011, 11:51
2
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  55% (hard)

Question Stats:

45% (01:25) correct 55% (01:08) wrong based on 33 sessions

HideShow timer Statistics

If xyz ≠ 0, is x(y + z) = 0?


(1) |y + z| = |y| + |z|

(2) |x + y| = |x| + |y|
[Reveal] Spoiler: OA

Last edited by wizardsasha on 13 Nov 2011, 10:40, edited 2 times in total.

Kudos [?]: 360 [0], given: 22

Manager
Manager
avatar
Joined: 16 Mar 2011
Posts: 170

Kudos [?]: 46 [0], given: 13

Re: If xyz ≠ 0, is x(y + z) = 0? [#permalink]

Show Tags

New post 21 Jun 2011, 12:08
Hmm I don't get the OA..

If xyz is not equal to zero it means neither value, x, y or z can be zero.

1) If we pick values for y and z, -2 and 0,5, then we get 1,5 = 2,5 which obviously doesn't fit. If we take -2 and -0,5 we get 2,5 = 2,5 which fits. In order to fit this y and z must therefore have the same sign.
Therefore it can either be negative or positive. Still, whether x(y+z)=0, now depends on the value of x. We can see from the question that if xyz is not equal to zero it means x is also not zero. So, if x can't equal zero, x(y+z), no matter the value of y+z, can not equal zero. Why is it C then, anyone?

Kudos [?]: 46 [0], given: 13

1 KUDOS received
Senior Manager
Senior Manager
avatar
Joined: 24 Mar 2011
Posts: 440

Kudos [?]: 215 [1], given: 20

Location: Texas
Re: If xyz ≠ 0, is x(y + z) = 0? [#permalink]

Show Tags

New post 21 Jun 2011, 12:32
1
This post received
KUDOS
I cannot think of scenario where statement A is not alone sufficient.
Statement A should alone give the value of exp as either +ve or -ve. So should be sufficient.

As per state statement 2, the value of the expression can be either 0 or -ve or +ve, so it is not sufficient.

i remember this Q i read somewhere and it was required to determine - x(y+z) >=0 , in that case the both statements will be required and OA should be C.

Last edited by agdimple333 on 21 Jun 2011, 12:45, edited 1 time in total.

Kudos [?]: 215 [1], given: 20

Manager
Manager
avatar
Joined: 16 Mar 2011
Posts: 170

Kudos [?]: 46 [0], given: 13

Re: If xyz ≠ 0, is x(y + z) = 0? [#permalink]

Show Tags

New post 21 Jun 2011, 12:34
Hmm, this calls for an expert :D

Kudos [?]: 46 [0], given: 13

Manager
Manager
avatar
Joined: 11 Apr 2011
Posts: 104

Kudos [?]: 32 [0], given: 16

Re: If xyz ≠ 0, is x(y + z) = 0? [#permalink]

Show Tags

New post 27 Jun 2011, 10:56
my take -

1. both z and y are either +ve or -ve. insufficient
2. both x and y are either +ve or -ve. insufficient.

Combining both, all of x, y and z are either +ve or -ve.
In both cases, x(y + z) != 0.
Answer is C.

Kudos [?]: 32 [0], given: 16

Math Forum Moderator
avatar
Joined: 20 Dec 2010
Posts: 1964

Kudos [?]: 2048 [0], given: 376

Re: If xyz ≠ 0, is x(y + z) = 0? [#permalink]

Show Tags

New post 27 Jun 2011, 11:10
agdimple333 wrote:
I cannot think of scenario where statement A is not alone sufficient.
Statement A should alone give the value of exp as either +ve or -ve. So should be sufficient.

As per state statement 2, the value of the expression can be either 0 or -ve or +ve, so it is not sufficient.

i remember this Q i read somewhere and it was required to determine - x(y+z) >=0 , in that case the both statements will be required and OA should be C.


I agree with this. Anyone thinks otherwise? Please give me an example where A alone fails.

Ans: "A"
_________________

~fluke

GMAT Club Premium Membership - big benefits and savings

Kudos [?]: 2048 [0], given: 376

1 KUDOS received
Manager
Manager
avatar
Joined: 11 Apr 2011
Posts: 104

Kudos [?]: 32 [1], given: 16

Re: If xyz ≠ 0, is x(y + z) = 0? [#permalink]

Show Tags

New post 27 Jun 2011, 11:33
1
This post received
KUDOS
I interpreted the question wrongly, A only can fulfill the condition.

Kudos [?]: 32 [1], given: 16

Director
Director
avatar
Joined: 01 Feb 2011
Posts: 726

Kudos [?]: 143 [0], given: 42

Re: If xyz ≠ 0, is x(y + z) = 0? [#permalink]

Show Tags

New post 28 Jun 2011, 19:50
A alone is sufficient to answer this question.

1. Sufficient

we have y>0 z>0 or y<0 z<0

also x is not equal to 0 . so x(y+z) will never be equal to 0.

2. Not sufficient

x>0 y>0 or x<0 y<0 . Also z is not equal to 0.

But if y=-z then x(y+z) can be 0.
if y is not equal to -z , then x(y+z) cannot be 0.

Answer is A.

Kudos [?]: 143 [0], given: 42

Senior Manager
Senior Manager
User avatar
Joined: 03 Mar 2010
Posts: 422

Kudos [?]: 360 [0], given: 22

Schools: Simon '16 (M)
Re: If xyz ≠ 0, is x(y + z) = 0? [#permalink]

Show Tags

New post 28 Jun 2011, 23:18
This question is from Question Set 18, Q# 32. I double checked the answer there. It says C.
_________________

My dad once said to me: Son, nothing succeeds like success.

Kudos [?]: 360 [0], given: 22

Current Student
avatar
Joined: 08 Jan 2009
Posts: 323

Kudos [?]: 158 [0], given: 7

GMAT 1: 770 Q50 V46
Re: If xyz ≠ 0, is x(y + z) = 0? [#permalink]

Show Tags

New post 29 Jun 2011, 00:27
I agree this is A.

Given 1 is true, x(y+z) will never equal zero.
However, given 2 is true, x(y+z) can equal zero or not

Kudos [?]: 158 [0], given: 7

Intern
Intern
User avatar
Joined: 08 Feb 2010
Posts: 45

Kudos [?]: 5 [0], given: 1

Concentration: Leadership, International Business
Schools: INSEAD Jan '13
GMAT 1: 670 Q50 V31
WE: Project Management (Energy and Utilities)
Re: If xyz ≠ 0, is x(y + z) = 0? [#permalink]

Show Tags

New post 29 Jun 2011, 04:47
Hi,

I agree with +ve / -ve explaination. Infact i also thought it the same way before even looking at the answers.

Cheers.

Kudos [?]: 5 [0], given: 1

Manager
Manager
User avatar
Joined: 14 Feb 2010
Posts: 159

Kudos [?]: 112 [0], given: 8

Location: Banaglore
Re: If xyz ≠ 0, is x(y + z) = 0? [#permalink]

Show Tags

New post 04 Jul 2011, 01:31
jamifahad wrote:
***Warning!!!! Debatable OA*****

\(If \hspace{2} xyz \ne 0, \hspace{1} is \hspace{3} x(y+z)=0?\)

\(1) \hspace{4} |y+z| = |y|+|z|\)

\(2) \hspace{4} |x+y| = |x|+|y|\)



Given : xyz not equal to 0 therefore x not equal to 0 , y not equal to 0 and z not equal to 0.

from condition 1 : |y+z| = |y|+|z| therefore both y and z are either positive or negative but not zero(this is given), therefore (y+z) will never be zero. This condtion is not sufficient beacuse if x=0 then x(y+z) becomes '0' else x(y+z) is non zero.

from condition 2 : |x+y| = |x| + |y| therefore x and y are either positive or negative but not zero(this is given) , therefore neither x =0 nor y = 0 . This condtion is not sufficient because what if z= -y then x(y+z) = 0.

From condition 1 and 2 neither x=0 nor y=-z (because they both are either positive or negative). Hence we can say that x(y+z) will never be zero.

Answer is C.

Kudos [?]: 112 [0], given: 8

Current Student
avatar
Joined: 08 Jan 2009
Posts: 323

Kudos [?]: 158 [0], given: 7

GMAT 1: 770 Q50 V46
Re: If xyz ≠ 0, is x(y + z) = 0? [#permalink]

Show Tags

New post 04 Jul 2011, 01:48
zuberahmed wrote:
jamifahad wrote:
***Warning!!!! Debatable OA*****

\(If \hspace{2} xyz \ne 0, \hspace{1} is \hspace{3} x(y+z)=0?\)

\(1) \hspace{4} |y+z| = |y|+|z|\)

\(2) \hspace{4} |x+y| = |x|+|y|\)



Given : xyz not equal to 0 therefore x not equal to 0

...

from condition 1 : ... This condtion is not sufficient beacuse if x=0 then x(y+z) becomes '0' else x(y+z) is non zero.


But, as you already said, x can't be zero.

Kudos [?]: 158 [0], given: 7

Expert Post
1 KUDOS received
Veritas Prep GMAT Instructor
User avatar
G
Joined: 16 Oct 2010
Posts: 7668

Kudos [?]: 17324 [1], given: 232

Location: Pune, India
Re: If xyz ≠ 0, is x(y + z) = 0? [#permalink]

Show Tags

New post 04 Jul 2011, 02:41
1
This post received
KUDOS
Expert's post
This is what I think when I go through this problem:

\(xyz \ne 0\) implies none of x, y and z is 0.
Question: Is x(y+z) = 0?
Since x is not 0, the question is just:
Is (y + z) = 0? or Is y = -z?

1)\(\hspace{4} |y+z| = |y|+|z|\)
If y and z satisfy this relation, y cannot be equal to -z if they are not 0. This is so because

\(\hspace{4} |-z+z| = |-z|+|z|\)
\(\hspace{4} 0 = 2|z|\)
But z is not 0 so y is not equal to -z.

Hence we get a definite 'No' answer. It is sufficient.

2) \(\hspace{4} |x+y| = |x|+|y|\)
Doesn't give us relation between y and z so not sufficient.

Answer (A)
_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Get started with Veritas Prep GMAT On Demand for $199

Veritas Prep Reviews

Kudos [?]: 17324 [1], given: 232

GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 09 Sep 2013
Posts: 16763

Kudos [?]: 273 [0], given: 0

Premium Member
Re: If xyz ≠ 0, is x(y + z) = 0? [#permalink]

Show Tags

New post 13 Aug 2017, 11:36
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.
_________________

GMAT Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources

Kudos [?]: 273 [0], given: 0

Re: If xyz ≠ 0, is x(y + z) = 0?   [#permalink] 13 Aug 2017, 11:36
Display posts from previous: Sort by

If xyz ≠ 0, is x(y + z) = 0?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

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®.