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

It is currently 18 Apr 2019, 15:35

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 g(x) = 3x + sqrt x

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

Hide Tags

 
Intern
Intern
avatar
Joined: 08 Dec 2015
Posts: 23
If g(x) = 3x + sqrt x  [#permalink]

Show Tags

New post Updated on: 25 Feb 2016, 17:08
2
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

100% (00:36) correct 0% (00:00) wrong based on 19 sessions

HideShow timer Statistics

If \(g(x) = 3x + \sqrt {x}\), what is the value of \(g(d^2 +6d+9)\)?



(Chapter 5, Page 79 - In Action problem #2)

SEO was poor for this question. Also, this is more open ended practice so it's less GMAT like.

Originally posted by jwam2 on 25 Feb 2016, 15:31.
Last edited by ENGRTOMBA2018 on 25 Feb 2016, 17:08, edited 1 time in total.
Reformatted the question
Math Expert
User avatar
V
Joined: 02 Aug 2009
Posts: 7556
Re: If g(x) = 3x + sqrt x  [#permalink]

Show Tags

New post 25 Feb 2016, 19:23
jwamala wrote:
If \(g(x) = 3x + \sqrt {x}\), what is the value of \(g(d^2 +6d+9)\)?



(Chapter 5, Page 79 - In Action problem #2)

SEO was poor for this question. Also, this is more open ended practice so it's less GMAT like.


Hi,
1)\(g(x) = 3x + \sqrt {x}\)..
and \(g(d^2 +6d+9)\)..
so substitute x as d^2 +6d+9..
\(g(d^2 +6d+9) = 3(d^2 +6d+9) + \sqrt {d^2 +6d+9}\)..
\(3d^2+18d+27+d+3=3d^2+19d+30\)

or
2)\(3x + \sqrt {x}=\sqrt {x}(3\sqrt {x}+1)\)...
if\(x= d^2 +6d+9\), \(\sqrt{x}\)=\(\sqrt{(d+3)^2}\)..
\(\sqrt {x}(3\sqrt {x}+1)\)=\(\sqrt{(d+3)^2}(3\sqrt{(d+3)^2}+1)\)..
\(\sqrt{(d+3)^2}(3\sqrt{(d+3)^2}+1)\)...
=\((d+3)(3d+9+1)=(d+3)(3d+10)\)
_________________
Intern
Intern
avatar
Joined: 08 Dec 2015
Posts: 23
Re: If g(x) = 3x + sqrt x  [#permalink]

Show Tags

New post 25 Feb 2016, 19:54
The solutions suggest that "3d^2 + 17d + 24" is also an answer. I'm not fully convinced so I've posted it here.

Posted from my mobile device
Intern
Intern
avatar
Joined: 08 Dec 2015
Posts: 23
Re: If g(x) = 3x + sqrt x  [#permalink]

Show Tags

New post 25 Feb 2016, 20:15
I see but still not convinced on having a negative root.

Source: MGMAT Chapter 5, Page 79 - In Action problem #2)

Posted from my mobile device
Math Expert
User avatar
V
Joined: 02 Aug 2009
Posts: 7556
Re: If g(x) = 3x + sqrt x  [#permalink]

Show Tags

New post 25 Feb 2016, 20:19
1
jwamala wrote:
I see but still not convinced on having a negative root.

Source: MGMAT Chapter 5, Page 79 - In Action problem #2)

Posted from my mobile device


As per GMAT,
\(\sqrt{9}= 3\) and not -3..
only if it is given \(\sqrt{9}= |3|\), you take two values 3 and -3..

there must be some thing else given too to take -ive root as an option..

_________________
Intern
Intern
avatar
Joined: 08 Dec 2015
Posts: 23
Re: If g(x) = 3x + sqrt x  [#permalink]

Show Tags

New post 25 Feb 2016, 20:23
I agree with you; that's why I posted the question.

Posted from my mobile device
Intern
Intern
avatar
B
Joined: 16 Aug 2017
Posts: 8
Re: If g(x) = 3x + sqrt x  [#permalink]

Show Tags

New post 18 Aug 2017, 04:10
chetan2u wrote:
jwamala wrote:
I see but still not convinced on having a negative root.

Source: MGMAT Chapter 5, Page 79 - In Action problem #2)

Posted from my mobile device


As per GMAT,
\(\sqrt{9}= 3\) and not -3..
only if it is given \(\sqrt{9}= |3|\), you take two values 3 and -3..

there must be some thing else given too to take -ive root as an option..



Is this only as per GMAT or mathematics in General? bunuel?
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 54370
Re: If g(x) = 3x + sqrt x  [#permalink]

Show Tags

New post 18 Aug 2017, 04:19
GMP12 wrote:
chetan2u wrote:
jwamala wrote:
I see but still not convinced on having a negative root.

Source: MGMAT Chapter 5, Page 79 - In Action problem #2)

Posted from my mobile device


As per GMAT,
\(\sqrt{9}= 3\) and not -3..
only if it is given \(\sqrt{9}= |3|\), you take two values 3 and -3..

there must be some thing else given too to take -ive root as an option..



Is this only as per GMAT or mathematics in General? bunuel?


When the GMAT provides the square root sign for an even root, such as \(\sqrt{x}\) or \(\sqrt[4]{x}\), then the only accepted answer is the positive root.

That is, \(\sqrt{25}=5\), NOT +5 or -5. Even roots have only a positive value on the GMAT.

In contrast, the equation \(x^2=25\) has TWO solutions, +5 and -5.
_________________
GMAT Club Bot
Re: If g(x) = 3x + sqrt x   [#permalink] 18 Aug 2017, 04:19
Display posts from previous: Sort by

If g(x) = 3x + sqrt x

  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®.