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This doesn't seem right (problem with a question)

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jlevi.esquire
 Post subject: This doesn't seem right (problem with a question)
 Post Posted: Sun Mar 13, 2011 11:33 pm 
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Course Students


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If x is an integer and 4x < 100, what is x?

(1) 4(x + 1) – 4(x – 1) > 100
(2) 4(x + 1) + 4x > 100

In the explanation, it stipulates that X must be 1, 2, or 3... however, the question never says that X is a positive integer?

JL
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tim
 Post subject: Re: This doesn't seem right (problem with a question)
 Post Posted: Tue Mar 15, 2011 4:33 pm 
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ManhattanGMAT Staff


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Location: Southwest Airlines, seat 21C
the explanation does not state that x must be 1, 2, or 3. these were just example values used to test what would happen. the solution would remain unchanged if you tested non-positive integers as well..

(for the benefit of other students, the actual question has all the x's and x+1's or x-1's as exponents, i.e. powers of 4)

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Tim Sanders
Manhattan GMAT Instructor
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thakkar.sameer
 Post subject: Re: This doesn't seem right (problem with a question)
 Post Posted: Tue Jun 07, 2011 12:05 pm 
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hi

Can you please explain this with negative integers values for x ?

Sameer
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jnelson0612
 Post subject: Re: This doesn't seem right (problem with a question)
 Post Posted: Thu Jun 23, 2011 8:32 pm 
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ManhattanGMAT Staff


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Sameer, are you familiar with the concept that negative exponents cause you to take the reciprocal of the number and then apply the exponent? For example, 4^-2 is (1/4)^2, or 1/16. Test out some negative numbers and see if any of them are possible values for x in the statements.

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Jamie Nelson
ManhattanGMAT Instructor
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