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

It is currently 24 Jul 2014, 13:39

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

Exponents and Roots

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Intern
Intern
avatar
Joined: 19 Oct 2011
Posts: 6
Followers: 0

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

Exponents and Roots [#permalink] New post 28 Oct 2011, 02:35
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 1 sessions
Simplify the following fraction:

2^21/4^4(4^5-4^3)
Intern
Intern
avatar
Joined: 19 Oct 2011
Posts: 6
Followers: 0

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

Re: Exponents and Roots [#permalink] New post 28 Oct 2011, 04:12
answer is supposed to be: 2^7/15?!
Intern
Intern
avatar
Joined: 19 Oct 2011
Posts: 6
Followers: 0

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

Re: Exponents and Roots [#permalink] New post 28 Oct 2011, 09:55
Can anybody explain the way of calculation? That would be really great!
Manager
Manager
User avatar
Status: livin on a prayer!!
Joined: 12 May 2011
Posts: 125
Location: Australia
Followers: 0

Kudos [?]: 17 [0], given: 1

Re: Exponents and Roots [#permalink] New post 28 Oct 2011, 15:27
Hi Corinna,

Here is my working out.

First, let's simplify the bottom expression.

4^4 (4^5 -4^3)

Expand

4^9 - 4^7

Take out common factor

4^7 (4^2 - 1)

= 4^7 (15)

Turn the 4 into a base of 2, which is 2^2

So (2^2)^7 ( 15)

= 2^14 (15)

Now we can cancel out the 2^14 by the 2^21 on the top so the top becomes 2^7

So the answer is

2^7/15

I hope that makes sense.
_________________

Aim for the sky! (800 in this case)
If you like my post, please give me Kudos :)

Current Student
User avatar
Joined: 08 Jan 2009
Posts: 334
GMAT 1: 770 Q50 V46
Followers: 21

Kudos [?]: 76 [0], given: 7

GMAT Tests User
Re: Exponents and Roots [#permalink] New post 28 Oct 2011, 17:28
This question is a bit silly without answer choices as it's not clear when the simplification is finished, but anyways:

\frac{2^{21}}{4^4*(4^5-4^3)}

\frac{2^{21}}{2^8*(2^{10}-2^6)}

\frac{2^{21}}{2^{14}*(2^4-1)}

\frac{2^{7}}{2^4-1}

\frac{2^{7}}{15}

\frac{128}{15}
_________________

My Debrief

Re: Exponents and Roots   [#permalink] 28 Oct 2011, 17:28
    Similar topics Author Replies Last post
Similar
Topics:
1 Experts publish their posts in the topic Strategy for Exponents and Roots Patheinemann 3 28 Aug 2012, 13:02
Root/ Exponents...easy way? Impenetrable 2 29 Dec 2011, 21:31
Square of a exponent with root rxs0005 1 17 Jul 2010, 15:33
2 Experts publish their posts in the topic Exponents and Roots sac8513 3 03 Nov 2009, 14:59
Experts publish their posts in the topic Important question on roots and exponents benjiboo 5 02 Nov 2009, 10:52
Display posts from previous: Sort by

Exponents and Roots

  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®.