3^x - 3^x-1 = 162, x (x - 1) = ? For some reason I'm stumped : Quant Question Archive [LOCKED]
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 18 Jan 2017, 22:55

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# 3^x - 3^x-1 = 162, x (x - 1) = ? For some reason I'm stumped

Author Message
Director
Joined: 10 Feb 2006
Posts: 658
Followers: 3

Kudos [?]: 459 [0], given: 0

3^x - 3^x-1 = 162, x (x - 1) = ? For some reason I'm stumped [#permalink]

### Show Tags

09 Jul 2006, 11:16
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

3^x - 3^x-1 = 162, x (x - 1) = ?

For some reason I'm stumped on this one. Do we have an exponent rule when doing addition???

Thank!!
_________________

GMAT the final frontie!!!.

Intern
Joined: 03 Jan 2006
Posts: 25
Followers: 0

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

### Show Tags

09 Jul 2006, 11:23
3^x - 3^x-1 = 162, x (x - 1) = ?

For some reason I'm stumped on this one. Do we have an exponent rule when doing addition???

Thank!!

3^x - 3^(x-1) = 162
=> {3^(x-1)} * {3-1} = 162 (Taking 3^(x-1) term common)
=> 3^(x-1) = 162/2
=> 3^(x-1) = 81
=> 3^(x-1) = 3^4
=> x-1 = 4
=> x=5

Last edited by shahsac on 09 Jul 2006, 11:41, edited 2 times in total.
Manager
Joined: 16 Apr 2006
Posts: 79
Followers: 1

Kudos [?]: 2 [0], given: 0

### Show Tags

09 Jul 2006, 11:24
3^x - 3^x-1 = 162, x (x - 1) = ?

For some reason I'm stumped on this one. Do we have an exponent rule when doing addition???

Thank!!

3^x[1-1/3]=162
3^x[2/3]=162
3^x=243
x=5
x(x-1)=20
Director
Joined: 10 Feb 2006
Posts: 658
Followers: 3

Kudos [?]: 459 [0], given: 0

### Show Tags

09 Jul 2006, 11:39
skandhadarshan, how were you able to get the common of 1/3 ???
_________________

GMAT the final frontie!!!.

Intern
Joined: 03 Jan 2006
Posts: 25
Followers: 0

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

### Show Tags

09 Jul 2006, 11:44
skandhadarshan, how were you able to get the common of 1/3 ???

Because he took 3^x as common term

3^(x-1) can also be written as {(3^x)/3}
So when 3^x is taken out as a common term....1/3 is left behind.......
Director
Joined: 10 Feb 2006
Posts: 658
Followers: 3

Kudos [?]: 459 [0], given: 0

### Show Tags

09 Jul 2006, 12:10
gotcha!! Thank you gentleman.
_________________

GMAT the final frontie!!!.

09 Jul 2006, 12:10
Display posts from previous: Sort by