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

It is currently 23 Oct 2014, 06:53

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

For which of the following values of x is the equation

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
SVP
SVP
avatar
Joined: 21 Jul 2006
Posts: 1551
Followers: 8

Kudos [?]: 234 [0], given: 1

For which of the following values of x is the equation [#permalink] New post 08 Dec 2007, 08:19
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
For which of the following values of x is the equation (x+4)!/x! = (x+1)!

a) 6
b) 7
c) 8
d) 9
e) 10



Please provide explanation to your answer.
CEO
CEO
User avatar
Joined: 29 Aug 2007
Posts: 2500
Followers: 54

Kudos [?]: 512 [0], given: 19

Re: PS: Factorials [#permalink] New post 08 Dec 2007, 10:34
tarek99 wrote:
For which of the following values of x is the equation (x+4)!/x! = (x+1)!

a) 6
b) 7
c) 8
d) 9
e) 10

Please provide explanation to your answer.



(x+4)! / x! = (x+1)!
(x+4) (x+3) (x+2) (x+1) (x!) / (x!) = (x+1) (x!)
(x+4) (x+3) (x+2) = (x!)

plugg it: got 6.
Director
Director
User avatar
Joined: 12 Jul 2007
Posts: 867
Followers: 12

Kudos [?]: 201 [0], given: 0

Re: PS: Factorials [#permalink] New post 08 Dec 2007, 10:40
GMAT TIGER wrote:
tarek99 wrote:
For which of the following values of x is the equation (x+4)!/x! = (x+1)!

a) 6
b) 7
c) 8
d) 9
e) 10

Please provide explanation to your answer.



(x+4)! / x! = (x+1)!
(x+4) (x+3) (x+2) (x+1) (x!) / (x!) = (x+1) (x!)
(x+4) (x+3) (x+2) = (x!)

plugg it: got 6.


yup, and you can simplify it out when plugging it in as well.

using 6:

10*9*8 = 6*5*4*3*2
9*8 = 6*4*3
3*2 = 6

checks out
SVP
SVP
avatar
Joined: 21 Jul 2006
Posts: 1551
Followers: 8

Kudos [?]: 234 [0], given: 1

 [#permalink] New post 08 Dec 2007, 12:13
You guys are right and the OA is A. however, i need to correct your calculation here:

"yup, and you can simplify it out when plugging it in as well.

using 6:

10*9*8*7 = 7*6*5*4*3*2
7 = 7 "

you're approach is correct, however, you forgot the 7, which i've added and have highlighted for you.
Director
Director
User avatar
Joined: 12 Jul 2007
Posts: 867
Followers: 12

Kudos [?]: 201 [0], given: 0

 [#permalink] New post 08 Dec 2007, 12:16
tarek99 wrote:
You guys are right and the OA is A. however, i need to correct your calculation here:

"yup, and you can simplify it out when plugging it in as well.

using 6:

10*9*8*7 = 7*6*5*4*3*2
9*8*7 = 7*6*4*3
7 = 7 "

you're approach is correct, however, you forgot the 7, which i've added and have highlighted for you.


(x+1) appeared on both sides of the equation and can be canceled out before plugging in x. you can leave it in if you want, it's just unnecessary
  [#permalink] 08 Dec 2007, 12:16
    Similar topics Author Replies Last post
Similar
Topics:
3 Experts publish their posts in the topic For which of the following values of x is nifoui 4 21 Mar 2010, 10:00
Experts publish their posts in the topic For which of the following values of X is the equation dynamo 7 29 Dec 2007, 01:17
For which of the following values of x is the equation hsk 2 09 Jun 2007, 15:15
For which of the following values of x is the equation = (x blshah 6 11 Dec 2005, 16:40
For which of the following values of x is the equation joemama142000 2 30 Oct 2005, 21:04
Display posts from previous: Sort by

For which of the following values of x is the equation

  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®.