document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1096819>Question 1096819</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Can someone help me to finish this problem. Thanks for help.<BR>\n" );
document.write( "The pressure of the oil in reservoir tends to drop with time. By taking sample pressure readings for a particular oil reservoir, petroleum engineers have found that the change ..... is given by the function P(t)=t^3-18t^2+81t where t is time in years from the date of the first reading.<BR>\n" );
document.write( "a) Find P(0), P(3), P(5), P(10)<BR>\n" );
document.write( "Over what period is the change(drop) in pressure decreasing; 3 to 10 or 3 to 9? <BR>\n" );
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document.write( "a) P(0)=0 right?<BR>\n" );
document.write( "b) P(3)=3^-18*3^2+81*3<BR>\n" );
document.write( "   P(3)=90<BR>\n" );
document.write( "c) P(5)=?<BR>\n" );
document.write( "d) P(10)=?\r<BR>\n" );
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document.write( "How to do the P(5) and P(10)? <BR>\n" );
document.write( "Over what period is the change(drop) in pressure decreasing; 3 to 10 or 3 to 9?  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #711213 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=711213\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> P(0) is 0.<BR>\n" );
document.write( "P(3)=3^3-18(3^2)+81(3)=27-162+243=108.  This is a cubic equation, and the first term is cubed.<BR>\n" );
document.write( "P(5)=5^3-18(25)+81(5)=125-450+405=80<BR>\n" );
document.write( "P(10)=10^3-18(100)+81(10)=1000-1800+810=10.<BR>\n" );
document.write( "Check P(9)=9^3-18(81)+81(9)=729-1458+729=0<BR>\n" );
document.write( "The drop is from P(3) to P(9), and the graph shows that as well.<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=graph%28300%2C300%2C-10%2C15%2C-50%2C200%2Cx%5E3-18x%5E2%2B81x%29 ALIGN=MIDDLE  ALT=\"graph%28300%2C300%2C-10%2C15%2C-50%2C200%2Cx%5E3-18x%5E2%2B81x%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > </SPAN>\n" );
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