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If g is an integer what is the value of (-1)^(g^4-1)

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If g is an integer what is the value of (-1)^(g^4-1) [#permalink] New post 21 Dec 2008, 08:55
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Question Stats:

35% (02:06) correct 65% (01:08) wrong based on 108 sessions
If g is an integer what is the value of (-1)^{g^4 - 1} ?

(1) g^2<{1}
(2) g^2+2 g=0

Source: GMAT Club Tests - hardest GMAT questions
[Reveal] Spoiler: OA

Last edited by Bunuel on 13 Dec 2013, 06:08, edited 2 times in total.
Updated.
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Re: What is the value of (-1)^{g^4 + g - 1} ? 1. g is an [#permalink] New post 19 Dec 2012, 05:40
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ugimba wrote:
What is the value of (-1)^{g^4 + g - 1} ?

1. g is an integer
2. g is even

[Reveal] Spoiler: OA
D

Source: GMAT Club Tests - hardest GMAT questions

shouldn't we consider negative values for option 1? ( 'g' is integer)? in this case, then A wont fit right?


BELOW IS REVISED VERSION OF THIS QUESTION:
If g is an integer what is the value of (-1)^{g^4 - 1} ?

(1) g^2<{1}
(2) g^2+2 g=0

SOLUTION:
(1) g^2<{1} --> since g is an integer then g=0. Sufficient to calculate the value of (-1)^{g^4 - 1}.

(2) g^2+2g=0 --> g(g+2)=0 --> g=0 or g=-2. Since both possible values of g are even then (-1)^{even^4 - 1}=(-1)^{even-1}=(-1)^{odd}=-1. Sufficient.

Answer: D.
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Re: What is the value of (-1)^{g^4 + g - 1} ? 1. g is an [#permalink] New post 19 Dec 2012, 16:14
good question really tricky, i went on select B in hurry
VP
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Status: Final Lap Up!!!
Affiliations: NYK Line
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GMAT 2: 530 Q44 V20
GMAT 3: 630 Q45 V31
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WE: Engineering (Transportation)
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Kudos [?]: 247 [0], given: 67

Re: What is the value of (-1)^{g^4 + g - 1} ? 1. g is an [#permalink] New post 19 Dec 2012, 16:19
Bunuel wrote:
ugimba wrote:
What is the value of (-1)^{g^4 + g - 1} ?

1. g is an integer
2. g is even

[Reveal] Spoiler: OA
D

Source: GMAT Club Tests - hardest GMAT questions

shouldn't we consider negative values for option 1? ( 'g' is integer)? in this case, then A wont fit right?


BELOW IS REVISED VERSION OF THIS QUESTION:
If g is an integer what is the value of (-1)^{g^4 - 1} ?

(1) g^2<{1}
(2) g^2+2 g=0

SOLUTION:
(1) g^2<{1} --> since g is an integer then g=0. Sufficient to calculate the value of (-1)^{g^4 - 1}.

(2) g^2+2g=0 --> g(g+2)=0 --> g=0 or g=-2. Since both possible values of g are even then (-1)^{even^4 - 1}=(-1)^{even-1}=(-1)^{odd}=-1. Sufficient.

Answer: D.



Superb question, since g^2<1 g cannot have any value except zero had it been g<1 than the answer would have been B
Re: What is the value of (-1)^{g^4 + g - 1} ? 1. g is an   [#permalink] 19 Dec 2012, 16:19
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