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Advanced GMAT Book Try it 4-9 Inequality

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tomslawsky
 Post subject: Advanced GMAT Book Try it 4-9 Inequality
 Post Posted: Tue Jun 28, 2011 11:22 pm 
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Students


Posts: 138
Q: a not 0,

is 1/a> a/b^4 + 3?

1) a^2 = B^2

2) a^2 = b^4


Now, i am aware that when you "cross multiply", for 1, you have to take into consideration whether a is positive or negative, so in the answer in the book, the flow chart looks reasonable to me. However, in the explanation, the author states

"b^2 is positive, so a is positive"

I am completely lost here. If b^ is positive, can't a still be + or - and a^2 still = b^2, as all squared terms are positive. Why, in this case, are we able to ignore the case in which a is negative. Please help, I've spent literally 2-3 hours on this 1 question and I am too obsessive to move on.....haha.

thanks
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RonPurewal
 Post subject: Re: Advanced GMAT Book Try it 4-9 Inequality
 Post Posted: Wed Jun 29, 2011 7:16 am 
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ManhattanGMAT Staff


Posts: 7146
this error has been reported to us; thanks for pointing it out.

if you see other errors, please contact us, as described by stacey here:
http://www.beatthegmat.com/mgmat-proble ... tml#377505

thanks.
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tomslawsky
 Post subject: Re: Advanced GMAT Book Try it 4-9 Inequality
 Post Posted: Thu Jun 30, 2011 7:04 am 
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Students


Posts: 138
thanks, Ron...im glad i actually do understand the problem now; shouldn't have doubted myself, but i get a bit obsessive when I can't figure things out!
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jnelson0612
 Post subject: Re: Advanced GMAT Book Try it 4-9 Inequality
 Post Posted: Sat Jul 02, 2011 11:00 pm 
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ManhattanGMAT Staff


Posts: 1857
Thanks Tom!

_________________
Jamie Nelson
ManhattanGMAT Instructor
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