NEW HERE? LEARN MORE
closeclose
Last visit was: 25 Apr 2024, 21:48 It is currently 25 Apr 2024, 21:48
Decision Tracker
My Rewards
New posts
New comers' posts

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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel

What is the value of (x - y)^4?

SORT BY:
Date
Kudos
Tags:
Find Similar Topics 
Show Tags
Hide Tags
User avatar
eresh
Manager
Manager
Joined: 05 Jul 2009
Posts: 107
Own Kudos [?]: 94 [1]
Given Kudos: 5
 Q48  V27
Send PM
What is the value of (x - y)^4? [#permalink] New post   Updated on: 03 Jul 2013, 00:34
1
Kudos
00:00
A
B
C
D
E

Difficulty:

25% (medium)

Question Stats:

67% (01:02) correct 33% (01:16) wrong based on 143 sessions
Hide Show timer Statistics
What is the value of (x - y)^4?

(1) The product of x and y is 7.
(2) x and y are integers

OPEN DISCUSSION OF THIS QUESTION IS HERE: what-is-the-value-of-x-y-128238.html
ShowHide Answer
Official Answer
C

Originally posted by eresh on 15 Oct 2009, 15:58.
Last edited by Bunuel on 03 Jul 2013, 00:34, edited 1 time in total.
Edited the question and added the OA
User avatar
B
yangsta8
Senior Manager
Senior Manager
Joined: 31 Aug 2009
Posts: 290
Own Kudos [?]: 1041 [0]
Given Kudos: 20
Location: Sydney, Australia
 Q49  V41
Send PM
Re: What is the value [#permalink] New post   15 Oct 2009, 16:08
Statement 1)
If xy = 7 then considering the following two scenarios
x = 7 y =17 then (x-y)^4 = 6^4
x = 14 y = ½ then (x-y)^4 = 13.5^4
Not suff.

Statement 2)
X and Y are integers means that x=1 y=7 or y=1 x=7, since 7 is prime it’s only factors are 1 and itself.
(1-7)^4 = -6^4
(7-1)^4 = 6^4
These are both equal hence sufficient.

ANS = B
User avatar
pittgreek
Intern
Intern
Joined: 04 Aug 2009
Posts: 33
Own Kudos [?]: 5 [0]
Given Kudos: 2
Location: pitt
Concentration: finance /supply chain
Send PM
Re: What is the value [#permalink] New post   15 Oct 2009, 16:22
x and y are integers only 7 and 1 is valid.. so its cannot be B.

both statements are required to solve the problem
User avatar
B
yangsta8
Senior Manager
Senior Manager
Joined: 31 Aug 2009
Posts: 290
Own Kudos [?]: 1041 [0]
Given Kudos: 20
Location: Sydney, Australia
 Q49  V41
Send PM
Re: What is the value [#permalink] New post   15 Oct 2009, 16:40
pittgreek wrote:
x and y are integers only 7 and 1 is valid.. so its cannot be B.

both statements are required to solve the problem


Sorry my working for B was actually assuming that the integers xy = 7 which actually implies ANS = C.

Silly mistake :shock:
User avatar
Economist
Senior Manager
Senior Manager
Joined: 01 Apr 2008
Posts: 392
Own Kudos [?]: 4074 [0]
Given Kudos: 18
Name: Ronak Amin
Schools: IIM Lucknow (IPMX) - Class of 2014
Send PM
Re: What is the value [#permalink] New post   15 Oct 2009, 23:06
yangsta8 wrote:
pittgreek wrote:
x and y are integers only 7 and 1 is valid.. so its cannot be B.

both statements are required to solve the problem


Sorry my working for B was actually assuming that the integers xy = 7 which actually implies ANS = C.

Silly mistake :shock:

When I saw your first post..I was like WTF...what am I doing today !! :) Answer SHOULD be C :)
User avatar
B
yangsta8
Senior Manager
Senior Manager
Joined: 31 Aug 2009
Posts: 290
Own Kudos [?]: 1041 [0]
Given Kudos: 20
Location: Sydney, Australia
 Q49  V41
Send PM
Re: What is the value [#permalink] New post   15 Oct 2009, 23:26
Economist wrote:
When I saw your first post..I was like WTF...what am I doing today !! :) Answer SHOULD be C :)


yep Friday is not a good day for brain activity hehe :)

Posted from my mobile device
User avatar
asterixmatrix
Manager
Manager
Joined: 12 Oct 2009
Posts: 65
Own Kudos [?]: 146 [0]
Given Kudos: 3
Send PM
Re: What is the value [#permalink] New post   16 Oct 2009, 01:07
eresh wrote:
What is the value of \((x - y)^4\)?
(1) The product of x and y is 7.
(2) x and y are integers.

Please answer what should be the best approach trying this kind of problem?


we would need both statements to solve. would go with C
User avatar
dasikasuneel
Intern
Intern
Joined: 17 Jun 2013
Posts: 2
Own Kudos [?]: 3 [0]
Given Kudos: 29
Schools: ISB '14
Send PM
Re: What is the value of (x - y)^4 ? (1) The product of [#permalink] New post   03 Jul 2013, 00:29
[quote="eresh"]What is the value of \((x - y)^4\)?
(1) The product of x and y is 7.
(2) x and y are integers.

ANSWER 1 ALONE SUFFICIENT

1) THE INTEGERS CAN BE 1 AND 7 OR -1 AND -7
(1-7) POWER 4 =-6 POWER 4. Therefore the value is 1296

If they are -1 and -7 still (-1-(-7)) = -1+7 = 6 (POWER 4) =1296. Therefore 1 alone sufficient.

2) Clearly insufficient.
User avatar
L
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 92915
Own Kudos [?]: 619054 [1]
Given Kudos: 81595
Send PM
CAT Tests Forum Quiz Mode
Re: What is the value of (x - y)^4 ? (1) The product of [#permalink] New post   03 Jul 2013, 00:37
1
Bookmarks
Expert Reply
dasikasuneel wrote:
eresh wrote:
What is the value of \((x - y)^4\)?
(1) The product of x and y is 7.
(2) x and y are integers.

ANSWER 1 ALONE SUFFICIENT

1) THE INTEGERS CAN BE 1 AND 7 OR -1 AND -7
(1-7) POWER 4 =-6 POWER 4. Therefore the value is 1296

If they are -1 and -7 still (-1-(-7)) = -1+7 = 6 (POWER 4) =1296. Therefore 1 alone sufficient.

2) Clearly insufficient.


Unfortunately that's not correct. Notice that we are NOT told that x and y are integers.

What is the value of (x - y)^4?

(1) The product of x and y is 7, well this one is clearly insufficient: if \(x=7\) and \(y=1\) then \((x-y)^4=6^4\) and if \(x=14\) and \(y=\frac{1}{2}\) then \((x-y)^4=(\frac{27}{2})^4\), two different answers, hence not sufficient.

(2) x and y are integers. Also insufficient.

(1)+(2) As \(x\) and \(y\) are integers and \(xy=7\) then either \(x\) and \(y\) are 1 and 7 (or vise-versa) or -1 and -7 (or vise-versa) in any case because of even power: \((x-y)^4=(7-1)^4=(1-7)^4=(-7+1)^4=(-1+7)^4=6^4\). Sufficient.

Answer: C.

OPEN DISCUSSION OF THIS QUESTION IS HERE: what-is-the-value-of-x-y-128238.html
GMAT Club Bot
gmatclubot
Re: What is the value of (x - y)^4 ? (1) The product of [#permalink]
03 Jul 2013, 00:37
Moderator:
Bunuel
Math Expert
92915 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne
Main navigation
GMAT Resources
Partners
MBA Resources
www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions