GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 16 Dec 2018, 21:09

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 in December
PrevNext
SuMoTuWeThFrSa
2526272829301
2345678
9101112131415
16171819202122
23242526272829
303112345
Open Detailed Calendar
  • 10 Keys to nail DS and CR questions

     December 17, 2018

     December 17, 2018

     06:00 PM PST

     07:00 PM PST

    Join our live webinar and learn how to approach Data Sufficiency and Critical Reasoning problems, how to identify the best way to solve each question and what most people do wrong.
  • FREE Quant Workshop by e-GMAT!

     December 16, 2018

     December 16, 2018

     07:00 AM PST

     09:00 AM PST

    Get personalized insights on how to achieve your Target Quant Score.

Which of the following is equivalent to (x + y)(x^2 + y^2)(x^4 + y^4)

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

Hide Tags

Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 51230
Which of the following is equivalent to (x + y)(x^2 + y^2)(x^4 + y^4)  [#permalink]

Show Tags

New post 12 Aug 2016, 07:59
00:00
A
B
C
D
E

Difficulty:

  15% (low)

Question Stats:

81% (01:14) correct 19% (01:24) wrong based on 154 sessions

HideShow timer Statistics

Senior Manager
Senior Manager
avatar
Joined: 23 Apr 2015
Posts: 305
Location: United States
Concentration: General Management, International Business
WE: Engineering (Consulting)
Re: Which of the following is equivalent to (x + y)(x^2 + y^2)(x^4 + y^4)  [#permalink]

Show Tags

New post 12 Aug 2016, 08:34
2
Given \((x+y)(x^2+y^2)(x^4+y^4)(x−y)\)

Re- arranging the terms \((x+y) ( x- y) (x^2+y^2)(x^4+y^4)\)
= \((x^2-y^2) (x^2+y^2)(x^4+y^4)\)
= \((x^4 - y^4)(x^4+y^4)\)
= \((x^8-y^8)\)
Answer is D
CEO
CEO
User avatar
D
Joined: 11 Sep 2015
Posts: 3240
Location: Canada
Which of the following is equivalent to (x + y)(x^2 + y^2)(x^4 + y^4)  [#permalink]

Show Tags

New post 12 Aug 2016, 11:05
Top Contributor
Bunuel wrote:
Which of the following is equivalent to (x + y)(x² + y²)(x⁴ + y⁴)(x - y)?

A. x - y
B. x² - y²
C. x⁴ - y⁴
D. x⁸ - y⁸
E. x⁸ - 4x²y² + y⁸


The approach that Senthil1981 used is perfect. It recognizes the various DIFFERENCES OF SQUARES hiding in the big expression.

HOWEVER, if you didn't see that approach, another (little longer) approach is the PLUG IN VALUES for x and y and then test the answer choices.
Here's what I mean:
Let's plug x = 2 and y = 1 into the given expression.
We get: (2 + 1)(2² + 1²)(2⁴ + 1⁴)(2 - 1) = (3)(4 + 1)(16 + 1) = (3)(5)(17) = 255

So, when x = 2 and y = 1, (x + y)(x² + y²)(x⁴ + y⁴)(x - y) is equal to 255
So, if an algebraic expression is EQUIVALENT to the given expression, it should evaluate to 255, when we plug in x = 2 and y = 1

Check the answer choices:
A. 2 - 1 = 1 NO GOOD
B. 2² - 1² = 3 NO GOOD
C. 2⁴ - 1⁴ = 15 NO GOOD
D. 2⁸ - 1⁸ = 255 PERFECT!!
E. 2⁸ - 4(2²)(1²) + 1⁸ = 241 NO GOOD

RELATED (TRICKY) PRACTICE QUESTION:

_________________

Test confidently with gmatprepnow.com
Image

Director
Director
User avatar
D
Joined: 27 May 2012
Posts: 633
Premium Member
Re: Which of the following is equivalent to (x + y)(x^2 + y^2)(x^4 + y^4)  [#permalink]

Show Tags

New post 20 Aug 2018, 23:36
Bunuel wrote:
Which of the following is equivalent to \((x + y)(x^2 + y^2)(x^4 + y^4)(x - y)\)?

A. x - y
B. x^2 - y^2
C. x^4 - y^4
D. x^8 - y^8
E. x^8 - 4x^2y^2 + y^8



Dear Moderator,
While going through the DS section of Algebra, found this PS question. Hope you will do the needful. Thank you.
_________________

- Stne

Intern
Intern
avatar
B
Joined: 04 May 2017
Posts: 13
Location: India
GMAT 1: 620 Q50 V24
GMAT 2: 650 Q49 V29
GMAT 3: 650 Q49 V31
GMAT 4: 680 Q48 V35
GMAT 5: 700 Q49 V36
GPA: 4
Reviews Badge
Re: Which of the following is equivalent to (x + y)(x^2 + y^2)(x^4 + y^4)  [#permalink]

Show Tags

New post 20 Aug 2018, 23:45
(x+y) (x-y) (x^2 + y^2) (x^4 + y^4)
= (x^2 - y^2) (x^2 + y^2) (x^4 + y^4)
= (x^4 - y^4) (x^4 + y^4)
= (x^8 - y^8)
GMAT Club Bot
Re: Which of the following is equivalent to (x + y)(x^2 + y^2)(x^4 + y^4) &nbs [#permalink] 20 Aug 2018, 23:45
Display posts from previous: Sort by

Which of the following is equivalent to (x + y)(x^2 + y^2)(x^4 + y^4)

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


Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| 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®.