document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=34690>Question 34690</A>This question is from textbook <A HREF=http://www.amazon.com/exec/obidos/ASIN/0201746328/algebrahomeworkh>intermediate algebra</A><BR>\n" );
document.write( ": <I><SPAN STYLE=\"word-break: break-all;\"> An arrow is launched upward. After t seconds,it's height(h) id given by the formula h=-16t+208t. After how many seconds will its height be 640 feet?<BR>\n" );
document.write( "Should this be solved using the zero-factor theorem? How should I set it up?<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 #20977 by </B><A HREF=/tutors/aboutme.mpl?userid=longjonsilver><B>longjonsilver(2297)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=longjonsilver><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=longjonsilver><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=20977\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> i think you meant to have: <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+h=-16t%5E2%2B208t+ ALIGN=MIDDLE  ALT=\"+h=-16t%5E2%2B208t+\"   DISABLED_style= \"max-width:90%; height:auto;\" >?\r<BR>\n" );
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document.write( "If so, then when height is 640, we get:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+640=-16t%5E2%2B208t+ ALIGN=MIDDLE  ALT=\"+640=-16t%5E2%2B208t+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+0=-16t%5E2%2B208t-640+ ALIGN=MIDDLE  ALT=\"+0=-16t%5E2%2B208t-640+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+16t%5E2+-+208t%2B640+=+0+ ALIGN=MIDDLE  ALT=\"+16t%5E2+-+208t%2B640+=+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+-+13t+%2B+40+=+0+ ALIGN=MIDDLE  ALT=\"+t%5E2+-+13t+%2B+40+=+0+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(t-8)(t-5) = 0<BR>\n" );
document.write( "so t-8=0 or t-5=0<BR>\n" );
document.write( "so t=5 or t=8\r<BR>\n" );
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document.write( "Two answers since the arrow reaches 640feet after 5 seconds, going up, then a further 3 seconds (the 8 seconds) it is again at 640 feet, coming down.\r<BR>\n" );
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document.write( "jon.<BR>\n" );
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