Last visit was: 22 Dec 2024, 19:53 It is currently 22 Dec 2024, 19:53

Close

GRE Prep 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, weā€™ll send you an estimated GRE 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
Verbal Expert
Joined: 18 Apr 2015
Posts: 30475
Own Kudos [?]: 36822 [2]
Given Kudos: 26100
Send PM
Verbal Expert
Joined: 18 Apr 2015
Posts: 30475
Own Kudos [?]: 36822 [0]
Given Kudos: 26100
Send PM
Intern
Intern
Joined: 12 Dec 2022
Posts: 21
Own Kudos [?]: 17 [1]
Given Kudos: 3
Send PM
Verbal Expert
Joined: 18 Apr 2015
Posts: 30475
Own Kudos [?]: 36822 [1]
Given Kudos: 26100
Send PM
Re: (-1)^-x=-1 and ? is a positive integer 0 [#permalink]
Expert Reply
1
Bookmarks
I think you are right sir even though it is reported as D

manipulating

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

\(1=-(-1^x)\)

\(1=1^x\)

\(x=1\)

B is greater than A
Intern
Intern
Joined: 09 Jan 2023
Posts: 3
Own Kudos [?]: 3 [0]
Given Kudos: 0
Send PM
Re: (-1)^-x=-1 and ? is a positive integer 0 [#permalink]
Answer should be D. Why does it show B?

On simplifying the left equation

(-1)^-x=-1
=> 1/((-1)^x) = -1
=> Which clearly means x is an odd number

And since x > 0 , it can be either of 1, 3, 5, 7 and on substituting the equation hold true, hence D
Verbal Expert
Joined: 18 Apr 2015
Posts: 30475
Own Kudos [?]: 36822 [0]
Given Kudos: 26100
Send PM
Re: (-1)^-x=-1 and ? is a positive integer 0 [#permalink]
Expert Reply
The original answer was D but to have -1 on RHS when we do have 1^x , x must be zero or 1

But the stem says that x is different from zero. X must be 1 then

Will see if BrushMyQuant has something to add
Moderator
Moderator
Joined: 02 Jan 2020
Status:GRE Quant Tutor
Posts: 1115
Own Kudos [?]: 974 [1]
Given Kudos: 9
Location: India
Concentration: General Management
Schools: XLRI Jamshedpur, India - Class of 2014
GMAT 1: 700 Q51 V31
GPA: 2.8
WE:Engineering (Computer Software)
Send PM
Re: (-1)^-x=-1 and ? is a positive integer 0 [#permalink]
1
Given that \((-1)^{-x}=-1\) and š‘„ is a positive integer ā‰  0

Quantity A = x

Now, \((-1)^{-x}=-1\)

For this to be true x should be an odd integer, as if x is even then \((-1)^{-x}=1\)
Ex: \((-1)^{-1}\)=\(\frac{1}{-1}\) = -1
Ex: \((-1)^{-2}\)=\(\frac{1}{(-1)^2}\) = 1
Ex: \((-1)^{-5}\)=\(\frac{1}{(-1)^5}\) = -1

Clearly, Quantity A can be greater than or less than or equal to Quantity B also.

So, Answer will be D
Hope it helps!

Watch the following video to learn the Basics of Exponents

Moderator
Moderator
Joined: 02 Jan 2020
Status:GRE Quant Tutor
Posts: 1115
Own Kudos [?]: 974 [0]
Given Kudos: 9
Location: India
Concentration: General Management
Schools: XLRI Jamshedpur, India - Class of 2014
GMAT 1: 700 Q51 V31
GPA: 2.8
WE:Engineering (Computer Software)
Send PM
Re: (-1)^-x=-1 and ? is a positive integer 0 [#permalink]
Where is X! given in the question?
sooshii wrote:
hi, can someone explain why is X != 1?
imo, the answer should be B
Moderator
Moderator
Joined: 02 Jan 2020
Status:GRE Quant Tutor
Posts: 1115
Own Kudos [?]: 974 [1]
Given Kudos: 9
Location: India
Concentration: General Management
Schools: XLRI Jamshedpur, India - Class of 2014
GMAT 1: 700 Q51 V31
GPA: 2.8
WE:Engineering (Computer Software)
Send PM
Re: (-1)^-x=-1 and ? is a positive integer 0 [#permalink]
1
Carcass wrote:
\(1=-(-1^x)\)


\(1=-(-1^x)\) = -(\((-1)^x\))
=> \((-1)^x\) = -1

Now, above statement will be true only for odd values of x
=> x can be 1, 3, 5...
=> Quantity A(x) can be smaller, equal to greater than Quantity B(3)

Hope it helps!
Moderator
Moderator
Joined: 02 Jan 2020
Status:GRE Quant Tutor
Posts: 1115
Own Kudos [?]: 974 [1]
Given Kudos: 9
Location: India
Concentration: General Management
Schools: XLRI Jamshedpur, India - Class of 2014
GMAT 1: 700 Q51 V31
GPA: 2.8
WE:Engineering (Computer Software)
Send PM
Re: (-1)^-x=-1 and ? is a positive integer 0 [#permalink]
1
Carcass : Updated OA to D
Prep Club for GRE Bot
Re: (-1)^-x=-1 and ? is a positive integer 0 [#permalink]
Moderators:
GRE Instructor
88 posts
GRE Forum Moderator
37 posts
Moderator
1115 posts
GRE Instructor
234 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne