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Q on q16 of MGMAT Question Bank - Equations, Inequalities&VI

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georginafleming
 Post subject: Q on q16 of MGMAT Question Bank - Equations, Inequalities&VI
 Post Posted: Sun May 22, 2011 8:33 am 
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Course Students


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Question no. 16 from MGMAT Question Bank - Equations, Inequalities, & VIC's:

If x and y are nonzero integers, is (x-1 + y-1)-1 > [(x-1)(y-1)]-1 ?

(1) x = 2y

(2) x + y > 0

MY QUESTION:
We can simplify the equation above to: does (xy/x+y) > xy? (which is what MGMAT does), but doesn't this then get simplified to (1/x+y)>1? And isn't 1/x+y NEVER bigger than 1, which answers the question without even looking at answer choices 1 or 2?

Please advise, thanks!
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georginafleming
 Post subject: Re: Q on q16 of MGMAT Question Bank - Equations, Inequalities&VI
 Post Posted: Sun May 22, 2011 8:47 am 
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Course Students


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I think I just found the answer to my own question: I can only divide both sides by xy if I know whether or not xy is 0, negative or positive, correct?
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jnelson0612
 Post subject: Re: Q on q16 of MGMAT Question Bank - Equations, Inequalities&VI
 Post Posted: Sun May 22, 2011 8:54 pm 
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ManhattanGMAT Staff


Posts: 1857
georginafleming wrote:
I think I just found the answer to my own question: I can only divide both sides by xy if I know whether or not xy is 0, negative or positive, correct?


Right, looks good to me! :-)

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Jamie Nelson
ManhattanGMAT Instructor
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