document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=247743>Question 247743</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Solve the following problems by defining the variable, writing a quadratic equation, solving it an then providing a written conclusion.\r<BR>\n" );
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document.write( " - A cannonball is fired form ground level on an arc described by h = -t^2 + 28t where \"h\" is the height in meters at any time \"t\" in seconds.  Determine the number of seconds it would take the ball to reach a height of 192m.  At what other point in its flight is also at 192m? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #180614 by </B><A HREF=/tutors/aboutme.mpl?userid=Alan3354><B>Alan3354(69443)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Alan3354><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=Alan3354><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=180614\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\">  A cannonball is fired form ground level on an arc described by h = -t^2 + 28t where \"h\" is the height in meters at any time \"t\" in seconds. Determine the number of seconds it would take the ball to reach a height of 192m. At what other point in its flight is also at 192m?<BR>\n" );
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document.write( "h(t) = -t^2 + 28t = 192<BR>\n" );
document.write( "t^2 - 28t + 192 = 0<BR>\n" );
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document.write( " <TR><TD  ALIGN=MIDDLE>Solved by <A  rel=nofollow HREF=http://wiki.algebra.com/index.php/Tutoring_-_pluggable_solvers>pluggable</A> solver: <A  rel=nofollow HREF=solve_quadratic_equation.solver>SOLVE quadratic equation (work shown, graph etc)</A></TD></TR>\n" );
document.write( "<TR><TD  ALIGN=LEFT>Quadratic equation <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=ax%5E2%2Bbx%2Bc=0 ALIGN=MIDDLE  ALT=\"ax%5E2%2Bbx%2Bc=0\"   DISABLED_style= \"max-width:90%; height:auto;\" > (in our case <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1x%5E2%2B-28x%2B192+=+0 ALIGN=MIDDLE  ALT=\"1x%5E2%2B-28x%2B192+=+0\"   DISABLED_style= \"max-width:90%; height:auto;\" >) has the following solutons:<BR>\n" );
document.write( "  <BR>\n" );
document.write( "  <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca ALIGN=MIDDLE  ALT=\"x%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
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document.write( "  For these solutions to exist, the <U>discriminant</U> <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=b%5E2-4ac ALIGN=MIDDLE  ALT=\"b%5E2-4ac\"   DISABLED_style= \"max-width:90%; height:auto;\" > should not be a negative number.<BR>\n" );
document.write( "  <BR>\n" );
document.write( "  First, we need to compute the discriminant <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=b%5E2-4ac ALIGN=MIDDLE  ALT=\"b%5E2-4ac\"   DISABLED_style= \"max-width:90%; height:auto;\" >: <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=b%5E2-4ac=%28-28%29%5E2-4%2A1%2A192=16 ALIGN=MIDDLE  ALT=\"b%5E2-4ac=%28-28%29%5E2-4%2A1%2A192=16\"   DISABLED_style= \"max-width:90%; height:auto;\" >.<BR>\n" );
document.write( "  <BR>\n" );
document.write( "  Discriminant d=16 is greater than zero. That means that there are two solutions: <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x%5B12%5D+=+%28--28%2B-sqrt%28+16+%29%29%2F2%5Ca ALIGN=MIDDLE  ALT=\"+x%5B12%5D+=+%28--28%2B-sqrt%28+16+%29%29%2F2%5Ca\"   DISABLED_style= \"max-width:90%; height:auto;\" >.<BR>\n" );
document.write( "  <BR>\n" );
document.write( "    <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x%5B1%5D+=+%28-%28-28%29%2Bsqrt%28+16+%29%29%2F2%5C1+=+16 ALIGN=MIDDLE  ALT=\"x%5B1%5D+=+%28-%28-28%29%2Bsqrt%28+16+%29%29%2F2%5C1+=+16\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "    <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x%5B2%5D+=+%28-%28-28%29-sqrt%28+16+%29%29%2F2%5C1+=+12 ALIGN=MIDDLE  ALT=\"x%5B2%5D+=+%28-%28-28%29-sqrt%28+16+%29%29%2F2%5C1+=+12\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
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document.write( "    Quadratic expression <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1x%5E2%2B-28x%2B192 ALIGN=MIDDLE  ALT=\"1x%5E2%2B-28x%2B192\"   DISABLED_style= \"max-width:90%; height:auto;\" > can be factored:<BR>\n" );
document.write( "  <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1x%5E2%2B-28x%2B192+=+%28x-16%29%2A%28x-12%29 ALIGN=MIDDLE  ALT=\"1x%5E2%2B-28x%2B192+=+%28x-16%29%2A%28x-12%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "  Again, the answer is: 16, 12.\n" );
document.write( "Here's your graph:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+1%2Ax%5E2%2B-28%2Ax%2B192+%29 ALIGN=MIDDLE  ALT=\"graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+1%2Ax%5E2%2B-28%2Ax%2B192+%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ></TD></TR>\n" );
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document.write( "It takes 12 seconds to reach 192 meters.<BR>\n" );
document.write( "It's again at 192 meters on its way down at 16 seconds.<BR>\n" );
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document.write( "The max height will be at 14 seconds, and the max is 196 meters.<BR>\n" );
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document.write( "This must be on a small planet or asteroid to have a gravity of 2 m/sec/sec.<BR>\n" );
document.write( "On Earth, it's 9.8 m/sec/sec, and the equation is -4.9t^2 for the acceleration term.<BR>\n" );
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