Find all School-related info fast with the new School-Specific MBA Forum

It is currently 16 Sep 2014, 05:31

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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

2^x-2^(x-2)=3(2^13) what is the value of x? 9 11 13 15 17

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Intern
Intern
avatar
Joined: 05 Sep 2008
Posts: 13
Followers: 0

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

2^x-2^(x-2)=3(2^13) what is the value of x? 9 11 13 15 17 [#permalink] New post 12 Sep 2008, 15:39
2^x-2^(x-2)=3(2^13) what is the value of x?

9
11
13
15
17
Senior Manager
Senior Manager
User avatar
Joined: 09 Oct 2007
Posts: 468
Followers: 1

Kudos [?]: 19 [0], given: 1

GMAT Tests User
Re: gmat prep another exponent [#permalink] New post 12 Sep 2008, 15:49
X = 15 = D

2^x - 2^(x-2) = 3 * 2^13
(2^2 * 2^x) - 2^x / 2^2 = 3 * 2^13
(2^2 * 2^x) - 2^x = 3 * 2^13 * 2^2
2^x (2^2 -1 ) = 3 * 2^15
2^x (3) = 3 * 2^15
2^x = 2^15
Intern
Intern
avatar
Joined: 05 Sep 2008
Posts: 13
Followers: 0

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

Re: gmat prep another exponent [#permalink] New post 12 Sep 2008, 16:14
asdert wrote:
X = 15 = D

2^x - 2^(x-2) = 3 * 2^13
(2^2 * 2^x) - 2^x / 2^2 = 3 * 2^13
(2^2 * 2^x) - 2^x = 3 * 2^13 * 2^2
2^x (2^2 -1 ) = 3 * 2^15
2^x (3) = 3 * 2^15
2^x = 2^15



how come 2^x is same as 2^2*2^x?
Senior Manager
Senior Manager
User avatar
Joined: 09 Oct 2007
Posts: 468
Followers: 1

Kudos [?]: 19 [0], given: 1

GMAT Tests User
Re: gmat prep another exponent [#permalink] New post 12 Sep 2008, 17:32
Since 2^(x-2) = 2^x / 2^2, I had to get the same numerator to the first part of the equation in order to subtract them.
Retired Moderator
User avatar
Joined: 18 Jul 2008
Posts: 997
Followers: 8

Kudos [?]: 71 [0], given: 5

GMAT Tests User
Re: gmat prep another exponent [#permalink] New post 12 Sep 2008, 19:34
For some reason, I got 11... What's the correct answer?
SVP
SVP
User avatar
Joined: 07 Nov 2007
Posts: 1829
Location: New York
Followers: 26

Kudos [?]: 450 [0], given: 5

GMAT Tests User
Re: gmat prep another exponent [#permalink] New post 12 Sep 2008, 19:36
Youngd8 wrote:
2^x-2^(x-2)=3(2^13) what is the value of x?

9
11
13
15
17


2^x-2^(x-2)=3(2^13)

--> 2^(x-2) *2^2- 2^(x-2)=3(2^13)
--> 2^(x-2) 3=3(2^13)
x=15
_________________

Your attitude determines your altitude
Smiling wins more friends than frowning

Re: gmat prep another exponent   [#permalink] 12 Sep 2008, 19:36
    Similar topics Author Replies Last post
Similar
Topics:
2^x - 2^(x-2) = 3(12^13) a) 9 b) 11 c) 13 d) 15 e) 17 tarek99 3 07 Nov 2008, 16:16
IF 2^x 2^(x-2) = 3(2^13), what is the value of x? 9 11 13 15 bsjames2 4 05 Jan 2008, 18:57
If 2^x- 2^(x-2) = 3*2^13, what is x? 9 11 13 15 17 r019h 2 04 Oct 2007, 19:28
If 2^x - 2^x-2 = 3(2^13). What is x? a)9 b)11 c)13 d)15 e)17 g1m2a3t406 7 19 Oct 2006, 14:24
2^x - 2^x-2 = 3(2^13) a) 9 b) 11 c) 13 d) 15 e) 17 $uckafr33 2 14 Oct 2006, 15:23
Display posts from previous: Sort by

2^x-2^(x-2)=3(2^13) what is the value of x? 9 11 13 15 17

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

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®.