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

It is currently 14 Oct 2019, 06:15

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

For what value of x between -5 and 1 inclusive, the value of 6x^2-x^4

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

Hide Tags

Find Similar Topics 
Director
Director
avatar
V
Joined: 18 Feb 2019
Posts: 580
Location: India
GMAT 1: 460 Q42 V13
GPA: 3.6
For what value of x between -5 and 1 inclusive, the value of 6x^2-x^4  [#permalink]

Show Tags

New post 14 Mar 2019, 09:40
3
00:00
A
B
C
D
E

Difficulty:

  65% (hard)

Question Stats:

50% (01:49) correct 50% (01:52) wrong based on 82 sessions

HideShow timer Statistics

For what value of x between -5 and 1 inclusive, the value of 6x^2–x^4-4 is greatest?

A. -5
B. -√5
C. -2
D. -√3
E. 1
Manager
Manager
User avatar
G
Joined: 21 Feb 2019
Posts: 125
Location: Italy
Premium Member
Re: For what value of x between -5 and 1 inclusive, the value of 6x^2-x^4  [#permalink]

Show Tags

New post 14 Mar 2019, 09:56
2
I differentiated:

\(12x - 4x^3 = 0\)

\(x^3 - 3x = 0\)

\(x(x^2 - 3) = 0\)

\(x = {0, +\sqrt{3}, -\sqrt{3}}\)

Since there is only \(-\sqrt{3}\) among the options, pick it up.

_________________
If you like my post, Kudos are appreciated! Thank you.


MEMENTO AUDERE SEMPER
Manager
Manager
avatar
G
Joined: 14 May 2018
Posts: 96
Location: India
Concentration: Finance, Entrepreneurship
GMAT 1: 710 Q49 V38
GPA: 4
Re: For what value of x between -5 and 1 inclusive, the value of 6x^2-x^4  [#permalink]

Show Tags

New post 14 Mar 2019, 12:55
kiran120680 wrote:
For what value of x between -5 and 1 inclusive, the value of 6x^2–x^4-4 is greatest?

A. -5
B. -√5
C. -2
D. -√3
E. 1



if we use -5,it will give a very large negative value, so cancel it. the larger the value,the more negative it will keep getting. just check for -\sqrt{3} and 1.

Ans:D
_________________
Please hit kudos if you like my answers.

GMAT:710 (Q49,V38,IR8,AWA5)
Director
Director
avatar
V
Joined: 18 Feb 2019
Posts: 580
Location: India
GMAT 1: 460 Q42 V13
GPA: 3.6
Re: For what value of x between -5 and 1 inclusive, the value of 6x^2-x^4  [#permalink]

Show Tags

New post 15 Mar 2019, 07:12
lucajava wrote:
I differentiated:

\(12x - 4x^3 = 0\)

\(x^3 - 3x = 0\)

\(x(x^2 - 3) = 0\)

\(x = {0, +\sqrt{3}, -\sqrt{3}}\)

Since there is only \(-\sqrt{3}\) among the options, pick it up.



Can you please explain elaborately
Manager
Manager
User avatar
G
Joined: 21 Feb 2019
Posts: 125
Location: Italy
Premium Member
Re: For what value of x between -5 and 1 inclusive, the value of 6x^2-x^4  [#permalink]

Show Tags

New post 15 Mar 2019, 10:32
1
kiran120680 wrote:
lucajava wrote:
I differentiated:

\(12x - 4x^3 = 0\)

\(x^3 - 3x = 0\)

\(x(x^2 - 3) = 0\)

\(x = {0, +\sqrt{3}, -\sqrt{3}}\)

Since there is only \(-\sqrt{3}\) among the options, pick it up.



Can you please explain elaborately


In math, the first derivative is used to find max. and min. values of a function. Starting from this point, i differentiated to find the \(x\) where the function takes the greatest value. Hope it's clear.
_________________
If you like my post, Kudos are appreciated! Thank you.


MEMENTO AUDERE SEMPER
LBS Moderator
User avatar
D
Joined: 04 Jun 2018
Posts: 646
Location: Germany
Concentration: General Management, Finance
GMAT 1: 730 Q47 V44
GPA: 3.4
WE: Analyst (Transportation)
Reviews Badge
Re: For what value of x between -5 and 1 inclusive, the value of 6x^2-x^4  [#permalink]

Show Tags

New post 13 May 2019, 10:33
GMAT Club Bot
Re: For what value of x between -5 and 1 inclusive, the value of 6x^2-x^4   [#permalink] 13 May 2019, 10:33
Display posts from previous: Sort by

For what value of x between -5 and 1 inclusive, the value of 6x^2-x^4

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





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