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# What is the value of (-1)^{g^4 + g - 1} ? 1. g is an

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Re: m06 # 4 [#permalink]  15 Dec 2010, 09:42
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Re: m06 # 4 [#permalink]  19 Dec 2011, 06:00
How is statement 2 sufficient?
G could be 1.2, or any even fraction
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Re: m06 # 4 [#permalink]  19 Dec 2011, 16:01
for some reason I thought the -1 was an exponent of g. Question is much easier now.
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Re: m06 # 4 [#permalink]  19 Dec 2011, 21:41
sl750 wrote:
How is statement 2 sufficient?
G could be 1.2, or any even fraction

Statement 2 says g is even. A fraction is not an even number. For example, 4/2 is a fraction which results in 2, an even number. But 4/2 itself is not an even number. The result of the calculation is an even number.

Now if you know that g is an even number, then g^4 will also be an even number. Thus (g^4 - g) will also be an even number. Thus you are subtracting 1 from an even number, and you will get an odd number. Thus (-1) is raised to an odd power. Thus you will always have the same answer = -1. SUFFICIENT.

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Re: What is the value of (-1)^{g^4 + g - 1} ? 1. g is an [#permalink]  19 Dec 2012, 05:40
Expert's post
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.

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Re: What is the value of (-1)^{g^4 + g - 1} ? 1. g is an [#permalink]  19 Dec 2012, 16:14
good question really tricky, i went on select B in hurry
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Re: What is the value of (-1)^{g^4 + g - 1} ? 1. g is an [#permalink]  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.

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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