document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=150725>Question 150725</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I am not sure how to categorize my question.  My nephew and I would like to find the right formula to calculate the following:\r<BR>\n" );
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document.write( "A rectangle<BR>\n" );
document.write( "Side A is   x + 20<BR>\n" );
document.write( "Side B is   x<BR>\n" );
document.write( "Area = 576\r<BR>\n" );
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document.write( "We know that x = 16 but we do not know a formula that gives us this answer (16).\r<BR>\n" );
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document.write( "Any help would be greatly appreciated\r<BR>\n" );
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document.write( "Paul </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #110649 by </B><A HREF=/tutors/aboutme.mpl?userid=nerdybill><B>nerdybill(7384)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=nerdybill><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=nerdybill><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=110649\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> .<BR>\n" );
document.write( "The problem assumes that you know the formula for any rectangle is:<BR>\n" );
document.write( "area = width * length<BR>\n" );
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document.write( "Therefore, if you have:<BR>\n" );
document.write( "Side A is x + 20<BR>\n" );
document.write( "Side B is x<BR>\n" );
document.write( "Area = 576 <BR>\n" );
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document.write( "Then, your formula would be:<BR>\n" );
document.write( "576 = x(x+20)<BR>\n" );
document.write( "576 = x^2 + 20x<BR>\n" );
document.write( "0 = x^2 + 20x - 576<BR>\n" );
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document.write( "Factoring the right side we have:<BR>\n" );
document.write( "0 = (x-16)(x+36)<BR>\n" );
document.write( "the solutions are then<BR>\n" );
document.write( "x = {-36, 16}<BR>\n" );
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document.write( "It doesn't make sense to have a \"negative\" length for a side therefore the solution MUST be:<BR>\n" );
document.write( "x = 16 (Side B)<BR>\n" );
document.write( "and<BR>\n" );
document.write( "x+20 = 36 (Side A)\r<BR>\n" );
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document.write( " </SPAN>\n" );
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