document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1114937>Question 1114937</A>: <I><SPAN STYLE=\"word-break: break-all;\">  If x thousand dollars is spent on advertising brush cutters the amount of brush cutters sold will be determined by the function <BR>\n" );
document.write( "B(x) = 2300 + 125/x &#8722; 517/x^2 for 3 &#8804; x &#8804; 12<BR>\n" );
document.write( "a. At what rate will sales be changing when $6000 is spent on advertising?<BR>\n" );
document.write( "b. At what rate will sales be changing when $9000 is spent on advertising?<BR>\n" );
document.write( "c. Are sales increasing or decreasing for the level of advertising expenditure in parts (a) and (b) above?<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 #729851 by </B><A HREF=/tutors/aboutme.mpl?userid=Boreal><B>Boreal(15235)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Boreal><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=Boreal><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=729851\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> B(x) = 2300 + 125/x &#8722; 517/x^2 for 3 &#8804; x &#8804; 12<BR>\n" );
document.write( "B(6)=2300-125/6+517/36=2300+20.83-14.36=2306.47<BR>\n" );
document.write( "B'(x)=-125x^(-2)+2(517)^x^(-3)<BR>\n" );
document.write( "=-125/x^2+1034/x^(-3)<BR>\n" );
document.write( "B'(6)=1034/216-125/36=+1.315 or $1315 per brush cutter sold<BR>\n" );
document.write( "B'(9)=1034/729-125/81=0.287 or $215 per brush cutter sold.<BR>\n" );
document.write( "Both are increasing.<BR>\n" );
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