It is currently 17 Oct 2017, 16:03

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

X^8 - Y^8 =

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

Hide Tags

2 KUDOS received
SVP
SVP
avatar
Status: Graduated
Affiliations: HEC
Joined: 28 Sep 2009
Posts: 1635

Kudos [?]: 684 [2], given: 432

Concentration: Economics, Finance
GMAT 1: 730 Q48 V44
Premium Member
X^8 - Y^8 = [#permalink]

Show Tags

New post 13 Jul 2010, 18:42
2
This post received
KUDOS
8
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

68% (00:46) correct 32% (00:53) wrong based on 607 sessions

HideShow timer Statistics

X^8 - Y^8 =

A. \((X^4 - Y^4)^2\)
B. \((X^4 + Y^4)(X^2 + Y^2)(X + Y)(X - Y)\)
C. \((X^6 + Y^2)(X^2 - Y^6)\)
D. \((X^4 - Y^4)(X^2 - Y^2)(X - Y)(X + Y)\)
E. \((X^2 - Y^2)^4\)
[Reveal] Spoiler: OA

_________________

GMAT Club Premium Membership - big benefits and savings

Kudos [?]: 684 [2], given: 432

4 KUDOS received
Senior Manager
Senior Manager
avatar
Joined: 08 Jan 2009
Posts: 326

Kudos [?]: 176 [4], given: 5

Re: MGMAT Challenge Problem [#permalink]

Show Tags

New post 13 Jul 2010, 19:39
4
This post received
KUDOS
Apply a^2 - b^2 = (a-b)(a+b)

(x^4)^2 - (y^4)^2

( x^4 + y^4) ( x^4 - y^4)

( x^4 + y^4) (x^2+y^2)(x^2-y^2)

( x^4 + y^4) (x^2+y^2)(x+y)(x-y)

So B

Kudos [?]: 176 [4], given: 5

Manager
Manager
avatar
Joined: 03 Jun 2010
Posts: 172

Kudos [?]: 71 [0], given: 40

Location: United States (MI)
Concentration: Marketing, General Management
WE: Business Development (Consumer Products)
GMAT ToolKit User Reviews Badge
Re: MGMAT Challenge Problem [#permalink]

Show Tags

New post 14 Jul 2010, 05:44
Looks like 500-level question))

Kudos [?]: 71 [0], given: 40

2 KUDOS received
Ms. Big Fat Panda
Ms. Big Fat Panda
User avatar
Status: Three Down.
Joined: 09 Jun 2010
Posts: 1915

Kudos [?]: 2203 [2], given: 210

Concentration: General Management, Nonprofit
GMAT ToolKit User
Re: MGMAT Challenge Problem [#permalink]

Show Tags

New post 14 Jul 2010, 06:13
2
This post received
KUDOS
3
This post was
BOOKMARKED
The solution is just a basic application of the principle that \(x^2 - y^2 = (x+y)(x-y)\)

So, when we simplify, we treat \(x^8 = (x^4)^2 = ((x^2)^2)^2\)

So we get the following:

\(x^8 - y^8 = (x^4+y^4)(x^4-y^4) = (x^4+y^4)(x^2+y^2)(x^2 - y^2) =(x^4+y^4)(x^2+y^2)(x+y)(x-y)\)

So, the answer is B.

Kudos [?]: 2203 [2], given: 210

SVP
SVP
avatar
Status: Graduated
Affiliations: HEC
Joined: 28 Sep 2009
Posts: 1635

Kudos [?]: 684 [0], given: 432

Concentration: Economics, Finance
GMAT 1: 730 Q48 V44
Premium Member
Re: MGMAT Challenge Problem [#permalink]

Show Tags

New post 14 Jul 2010, 06:56
ulm wrote:
Looks like 500-level question))


Agreed. I personally think that it belongs in the 600-level category, but MGMAT considers it a 700-level question. I just wanted to stay as faithful to the question source as possible.

I'll post a harder one to make up for it! :wink:
_________________

GMAT Club Premium Membership - big benefits and savings

Kudos [?]: 684 [0], given: 432

Manager
Manager
User avatar
Joined: 12 Jun 2007
Posts: 124

Kudos [?]: 78 [0], given: 2

Re: MGMAT Challenge Problem [#permalink]

Show Tags

New post 16 Jul 2010, 00:24
I go with option B

It is definitely not a 700 level problem

Kudos [?]: 78 [0], given: 2

GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 09 Sep 2013
Posts: 16760

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

Premium Member
Re: X^8 - Y^8 = [#permalink]

Show Tags

New post 24 Aug 2014, 17:04
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

SVP
SVP
User avatar
Status: The Best Or Nothing
Joined: 27 Dec 2012
Posts: 1853

Kudos [?]: 2616 [0], given: 193

Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)
Re: X^8 - Y^8 = [#permalink]

Show Tags

New post 24 Aug 2014, 23:31
BM wrote:
X^8 - Y^8 =

A. \((X^4 - Y^4)^2\)
B. \((X^4 + Y^4)(X^2 + Y^2)(X + Y)(X - Y)\)
C. \((X^6 + Y^2)(X^2 - Y^6)\)
D. \((X^4 - Y^4)(X^2 - Y^2)(X - Y)(X + Y)\)
E. \((X^2 - Y^2)^4\)



I solved this is hardly 3 seconds, would tell how? :)

\(x^8 - y^8\)

It has even power(\(8 = 2^3\)) & -ve sign in between, so fully expandable to the least power of x & y i.e (x+y)

All +ve powers cannot be expanded, so out of the 5 options, just search for (x-y) & terms with high +ve powers

Only option B fits in
_________________

Kindly press "+1 Kudos" to appreciate :)

Kudos [?]: 2616 [0], given: 193

GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 09 Sep 2013
Posts: 16760

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

Premium Member
Re: X^8 - Y^8 = [#permalink]

Show Tags

New post 01 Sep 2015, 05:15
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

GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 09 Sep 2013
Posts: 16760

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

Premium Member
Re: X^8 - Y^8 = [#permalink]

Show Tags

New post 06 Sep 2016, 08:01
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: X^8 - Y^8 =   [#permalink] 06 Sep 2016, 08:01
Display posts from previous: Sort by

X^8 - Y^8 =

  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®.