document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=971156>Question 971156</A>: <I><SPAN STYLE=\"word-break: break-all;\"> a plane's distance in meters is described by the function s(t)=220t-15t^2-60In(t+1).\r<BR>\n" );
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document.write( "1)Find a function that describes the speed of the plane<BR>\n" );
document.write( "2)Find the value of time when the speed is 100ms^-1  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #593770 by </B><A HREF=/tutors/aboutme.mpl?userid=anand429><B>anand429(138)</B></A><img src=\"/images/stars/stars-09.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=anand429><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=anand429><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=593770\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Speed is given as time derivative of distance<BR>\n" );
document.write( "i.e. <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=speed=+d%28s%29%2Fd%28t%29 ALIGN=MIDDLE  ALT=\"speed=+d%28s%29%2Fd%28t%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "So, <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=speed+=+d%28220t-15t%5E2-60In%28t%2B1%29%29%2Fd%28t%29 ALIGN=MIDDLE  ALT=\"speed+=+d%28220t-15t%5E2-60In%28t%2B1%29%29%2Fd%28t%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "= <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=220+-2%2A15t+-+60%2F%28t%2B1%29 ALIGN=MIDDLE  ALT=\"220+-2%2A15t+-+60%2F%28t%2B1%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "= <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=220+-+30t+-+60%2F%28t%2B1%29 ALIGN=MIDDLE  ALT=\"220+-+30t+-+60%2F%28t%2B1%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >  Ans to part 1<BR>\n" );
document.write( "For part2, when speed is 100ms^-1, <BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=220+-+30t+-+60%2F%28t%2B1%29+=+100 ALIGN=MIDDLE  ALT=\"220+-+30t+-+60%2F%28t%2B1%29+=+100\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=30t+%2B+60%2F%28t%2B1%29=+120 ALIGN=MIDDLE  ALT=\"30t+%2B+60%2F%28t%2B1%29=+120\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=30t%5E2+%2B+30t+%2B+60+=+120t+%2B+120 ALIGN=MIDDLE  ALT=\"30t%5E2+%2B+30t+%2B+60+=+120t+%2B+120\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=30t%5E2+-+90t+-+60+=+0 ALIGN=MIDDLE  ALT=\"30t%5E2+-+90t+-+60+=+0\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t%5E2-3t-2+=+0 ALIGN=MIDDLE  ALT=\"t%5E2-3t-2+=+0\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+t+=+%283%2B-+sqrt%2817%29%29%2F2 ALIGN=MIDDLE  ALT=\"+t+=+%283%2B-+sqrt%2817%29%29%2F2\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "t=3.56 seconds ignoring negative value of t. </SPAN>\n" );
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