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

It is currently 26 Apr 2019, 08:55

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 3^(-x)+3^(-x)+3^(-x)=1, what is the value of x?

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

Hide Tags

 
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 54696
If 3^(-x)+3^(-x)+3^(-x)=1, what is the value of x?  [#permalink]

Show Tags

New post 16 Aug 2017, 00:30
00:00
A
B
C
D
E

Difficulty:

  15% (low)

Question Stats:

83% (00:44) correct 17% (01:13) wrong based on 153 sessions

HideShow timer Statistics

Intern
Intern
avatar
Joined: 02 Jul 2017
Posts: 10
Re: If 3^(-x)+3^(-x)+3^(-x)=1, what is the value of x?  [#permalink]

Show Tags

New post 16 Aug 2017, 00:39
3(3^-x)=3^(1-x)=1
Implies x=1

Sent from my XT1706 using GMAT Club Forum mobile app
Manager
Manager
avatar
S
Joined: 06 Jul 2014
Posts: 94
Location: India
Concentration: Finance, Entrepreneurship
GMAT 1: 660 Q48 V32
GMAT ToolKit User Reviews Badge
Re: If 3^(-x)+3^(-x)+3^(-x)=1, what is the value of x?  [#permalink]

Show Tags

New post 16 Aug 2017, 01:49
3/3^x=1; 3^1-x=3^0; 1-x=0; 1=x
Director
Director
User avatar
V
Joined: 04 Dec 2015
Posts: 750
Location: India
Concentration: Technology, Strategy
WE: Information Technology (Consulting)
GMAT ToolKit User
If 3^(-x)+3^(-x)+3^(-x)=1, what is the value of x?  [#permalink]

Show Tags

New post 16 Aug 2017, 07:16
Bunuel wrote:
If \(3^{-x}+3^{-x}+3^{-x}=1\), what is the value of x?

A. -1

B. -1/2

C. 1/3

D. 1/2

E. 1

\(3^{-x}+3^{-x}+3^{-x}=1\)

\(3^{-x}(1+1+1) = 1\)

\(3^{-x}(3) = 1\)

\(3^{(-x+1)} = 1\) ----- (i)

\(3^0 = 1\), Therefore substituting \(3^0\) in equation (i) we get;

\(3^{(-x+1)} = 3^0\)

\(-x+1 = 0\)

\(x = 1\)

Answer (E)...
Senior SC Moderator
avatar
V
Joined: 22 May 2016
Posts: 2654
If 3^(-x)+3^(-x)+3^(-x)=1, what is the value of x?  [#permalink]

Show Tags

New post 16 Aug 2017, 07:24
1
Bunuel wrote:
If \(3^{-x}+3^{-x}+3^{-x}=1\), what is the value of x?

A. -1

B. -1/2

C. 1/3

D. 1/2

E. 1

3\(^{-x}\) = \(\frac{1}{3^{x}}\)

\(\frac{1}{3^{x}}\) + \(\frac{1}{3^{x}}\) + \(\frac{1}{3^{x}}\) = 1

\(\frac{1}{3}\) + \(\frac{1}{3}\) + \(\frac{1}{3}\) = 1

x = 1

Answer E
_________________
Listen, are you breathing just a little, and calling it a life?
-- Mary Oliver



For practice SC questions with official explanations that were posted and moderated by the SC Team,
go to SC Butler here: https://gmatclub.com/forum/project-sc-butler-get-2-sc-questions-everyday-281043.html
Manager
Manager
avatar
B
Joined: 18 Jun 2017
Posts: 59
Re: If 3^(-x)+3^(-x)+3^(-x)=1, what is the value of x?  [#permalink]

Show Tags

New post 22 Aug 2017, 08:27
X should be 1.
Inverse 3^-x and equate LHS & RHS using base and exponent concepts.
Option E.
Director
Director
User avatar
P
Joined: 04 Sep 2015
Posts: 559
Location: India
WE: Information Technology (Computer Software)
Premium Member Reviews Badge
Re: If 3^(-x)+3^(-x)+3^(-x)=1, what is the value of x?  [#permalink]

Show Tags

New post 22 Aug 2017, 10:49
If 3−x+3−x+3−x=13−x+3−x+3−x=1, what is the value of x?

A. -1

B. -1/2

C. 1/3

D. 1/2

E. 1

=3/3^x=1
for this to be true only value of x can be 1, thus E is the correct answer.
GMAT Club Bot
Re: If 3^(-x)+3^(-x)+3^(-x)=1, what is the value of x?   [#permalink] 22 Aug 2017, 10:49
Display posts from previous: Sort by

If 3^(-x)+3^(-x)+3^(-x)=1, what is the value of 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®.