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

It is currently 25 May 2019, 20:15

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

If x^5-5x^3+4x is the product of consecutive positive integers

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
VP
VP
avatar
P
Joined: 07 Dec 2014
Posts: 1192
If x^5-5x^3+4x is the product of consecutive positive integers  [#permalink]

Show Tags

New post 06 Jul 2017, 19:37
1
1
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

67% (00:42) correct 33% (02:33) wrong based on 6 sessions

HideShow timer Statistics

If x^5-5x^3+4x is the product of consecutive positive integers, what is the range of the sequence?

A. 3
B. 4
C. 5
D. 6
E. 7

source:self

--== Message from the GMAT Club Team ==--

THERE IS LIKELY A BETTER DISCUSSION OF THIS EXACT QUESTION.
This discussion does not meet community quality standards. It has been retired.


If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.
Senior Manager
Senior Manager
User avatar
B
Joined: 28 Jun 2015
Posts: 290
Concentration: Finance
GPA: 3.5
Re: If x^5-5x^3+4x is the product of consecutive positive integers  [#permalink]

Show Tags

New post 06 Jul 2017, 19:47
gracie wrote:
If x^5-5x^3+4x is the product of consecutive positive integers, what is the range of the sequence?

A. 3
B. 4
C. 5
D. 6
E. 7

source:self


Let the integers be \(y-2, y-1, y, y+1, y+2\)
Range = \(y + 2 - y + 2 = 4\). Ans - B.
_________________
I used to think the brain was the most important organ. Then I thought, look what’s telling me that.
Retired Moderator
avatar
P
Joined: 22 Aug 2013
Posts: 1443
Location: India
Re: If x^5-5x^3+4x is the product of consecutive positive integers  [#permalink]

Show Tags

New post 06 Jul 2017, 19:54
1
x^5 - 5x^3 + 4x can be written as:
x (x^4 - 5x^2 + 4) = (take out x common)
x (x^4 - 4x^2 - x^2 + 4) = (factorising)
x {x^2(x^2-4) - 1(x^2-4)} =
x (x^2-1) (x^2-4) =
x (x-1)(x+1)(x-2)(x+2) OR (x-2)(x-1)x(x+1)(x+2)

Thus the above algebraic expression is the product of 5 consecutive integers.. Thus range = x+2 - (x-2) = 4.
Hence B answer

--== Message from the GMAT Club Team ==--

THERE IS LIKELY A BETTER DISCUSSION OF THIS EXACT QUESTION.
This discussion does not meet community quality standards. It has been retired.


If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.
GMAT Club Bot
Re: If x^5-5x^3+4x is the product of consecutive positive integers   [#permalink] 06 Jul 2017, 19:54
Display posts from previous: Sort by

If x^5-5x^3+4x is the product of consecutive positive integers

  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®.