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Re: IA Regents #37
Posted:
Jun 24, 2008 12:05 PM
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If yoiu examine the factors that give answers -9 and plus 6 I think you will realize thath the factors are incorrect, since (x+9)(x-6) do not give a sum 15x.? So the regents answer is the only correct one.?
-----Original Message-----
From: Dslederman@aol.com
To: nysmathab@mathforum.org
Sent: Wed, 18 Jun 2008 9:39 am
Subject: Re: IA Regents #37
In a message dated 6/18/2008 2:30:24 A.M. Eastern Daylight Time, msedfun@aol.com writes:
The width of the walkway is x.
The length of the walkway is x + 15
The equation for area is:? Length x Width
(x)(x+15) = 54? This is the correct equation, right?
x^2 + 15x = 54
x^2 + 15x - 54 = 0
(x + 9)(x - 6) = 0
x = -9, x = 6
Can someone please tell me where x=3 came from in the scoring guide?? According to most of my students, the width = 6, and the length? = 21.? One of my students did the problem using perimeter instead of area, and came up with 6 and 21 as well.? Have I been looking at too many papers, or are 3 and 18 incorrect in the scoring guide?
x^2 + 15x -54 = (x + 18)(x - 3)..which leads to x = 3 (rejecting x = - 18).
?
David Lederman
06-18-08
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