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No solution question

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intrepid17
 Post subject: No solution question
 Post Posted: Wed Apr 14, 2010 9:56 pm 
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Students


Posts: 9
Each of the following equations has at least one solution EXCEPT


a) -2power(n) = (-2)power(-n)


b) 2 power(-n) = (-2)power(n)

c) 2power(n) = (-2)power(-n)

d) (-2)power(n) = -2power(n)

e) (-2)power(-n) = -2power(-n)


Last edited by intrepid17 on Wed Apr 14, 2010 11:26 pm, edited 1 time in total.

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ps63739
 Post subject: Re: No solution question
 Post Posted: Wed Apr 14, 2010 11:03 pm 
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Students


Posts: 54
Question does not seem to be clear, can you please type the options correctly or provide a link to the question, please?
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tim
 Post subject: Re: No solution question
 Post Posted: Fri Apr 30, 2010 6:17 pm 
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ManhattanGMAT Staff


Posts: 2242
Location: Southwest Airlines, seat 21C
i hate to say it, but sometimes it's quicker to plug in cleverly chosen numbers to eliminate wrong answers than to do the math for real. When you're dealing with powers, try 0 and 1 first:

B and C both give you 1=1 when n=0, in other words n=0 is a solution for B and C and thus we can eliminate them.

Similarly, 1 is a solution for both D and E, so we can eliminate them.

Proving that A actually has no solution is, frankly, beyond the level of math that the GMAT typically requires in its problems..

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Tim Sanders
Manhattan GMAT Instructor
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shantascherla
 Post subject: Re: No solution question
 Post Posted: Tue Apr 12, 2011 12:23 pm 
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Course Students


Posts: 21
Tim I am stuck on this question.

Following your explanation - doesnt option 1 also give us the same result which is 1 when n = 0
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tim
 Post subject: Re: No solution question
 Post Posted: Wed Apr 13, 2011 7:48 pm 
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ManhattanGMAT Staff


Posts: 2242
Location: Southwest Airlines, seat 21C
plug 0 into A and you get -2^0 for the left side. evaluate the power first and 2^0 = 1. now apply the negative and you get -1

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Tim Sanders
Manhattan GMAT Instructor
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