document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=173716>Question 173716</A>: <I><SPAN STYLE=\"word-break: break-all;\"> the cost of operating a testing device for n minutes is given by\r<BR>\n" );
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document.write( "C(n) = 1.4n^2 - 35n + 270\r<BR>\n" );
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document.write( "find the number of minutes the device had to be operated to minimize the cost?<BR>\n" );
document.write( "what is the minimum cost?<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #128593 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=128593\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> C(n) = 1.4n^2 - 35n + 270<BR>\n" );
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document.write( "This is a parabola in standard form.  Since the 'a' coefficient (1.4) is positive, finding the vertex will give you the minimum.  <BR>\n" );
document.write( "The n coordinate = -b/2a<BR>\n" );
document.write( "-(-35)/2(1.4)<BR>\n" );
document.write( "(35)/(2.8)<BR>\n" );
document.write( "12.5 <BR>\n" );
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document.write( "find the number of minutes the device had to be operated to minimize the cost?<BR>\n" );
document.write( "12.5 minutes<BR>\n" );
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document.write( "what is the minimum cost?<BR>\n" );
document.write( "To find the cost, stuff n=12.5 into the cost equation:<BR>\n" );
document.write( "C(n) = 1.4n^2 - 35n + 270<BR>\n" );
document.write( "C(12.5) = 1.4(12.5)^2 - 35(12.5) + 270<BR>\n" );
document.write( "C(12.5) = 218.75 - 437.5 + 270<BR>\n" );
document.write( "C(12.5) = $51.25\r<BR>\n" );
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