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Function Strategy:Question 21:Page92:Equalities

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ashishparmar01
 Post subject: Function Strategy:Question 21:Page92:Equalities
 Post Posted: Sat Feb 28, 2009 1:05 pm 
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Course Students


Posts: 4
This question is from the 3rd edition of GMAT Strategy guide: Equalities, Inequalities and VICs: 3rd edition
Q21: For which of the following functions does f(x) = f(2-x)?
A) f(x) = x + 2
B) f(x) = 2x - x^2
C) f(x) = 2 - x
D) f(x) = (2 - x)^2
E) f(x) = x^2

The answer given is B, which is correct even by my calculations. But, I think, I see a flaw in the solution given in the book. By picking 4 as a number, for f(4) the solution is
2(4) - 4^2 = -8

But for f(2-4), the solution given is (2 - 4) - (2 - 4)^2 = -2-4 = -6

The two solutions do not equate. Instead the solution should have been
2(2 - 4) - (2 - 4)^2 = -4-4=-8

Is this correct or am I missing something?

Thanks
Ashish
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saurav.raaj
 Post subject: Re: Function Strategy:Question 21:Page92:Equalities
 Post Posted: Sat Feb 28, 2009 6:03 pm 
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Posts: 12
I think the answer is D!
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ashishparmar01
 Post subject: Re: Function Strategy:Question 21:Page92:Equalities
 Post Posted: Sat Feb 28, 2009 9:19 pm 
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Course Students


Posts: 4
Can you post your calculation?
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JonathanSchneider
 Post subject: Re: Function Strategy:Question 21:Page92:Equalities
 Post Posted: Thu Mar 05, 2009 2:41 am 
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ManhattanGMAT Staff


Posts: 480
Location: Durham, NC
The answer is indeed B. To the original poster: you are absolutely correct. This is an error we hope to fix in our next printing. Thanks for pointing it out here as well :)
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christiancryan
 Post subject: Re: Function Strategy:Question 21:Page92:Equalities
 Post Posted: Thu Mar 05, 2009 11:37 am 
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ManhattanGMAT Staff


Posts: 79
Thanks for the catch! Unfortunately, we only recently sent this particular book back to the printer for another print run, having incorporated other revisions, but we've added this fix to the list for the next round of edits. I appreciate your feedback.

Chris Ryan
Director of Instructor & Product Development
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