document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=551083>Question 551083</A>: <I><SPAN STYLE=\"word-break: break-all;\"> If a stone is tossed from the top of a 210 meter building, the height of the stone as a function of time is given by h(t) = -9.8t2 – 10t + 210, where t is in seconds, and height is in meters. After how many seconds will the stone hit the ground? Round to the nearest hundredth’s place; include units in your answer.\r<BR>\n" );
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document.write( "I got <BR>\n" );
document.write( "-10(9.8t^2 - 10t + 210)=0<BR>\n" );
document.write( "98t + 100t - 2100<BR>\n" );
document.write( "49t^2 + 50t - 1050<BR>\n" );
document.write( "t= 4.15 seconds\r<BR>\n" );
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document.write( "Am I close??  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #359405 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=359405\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> If a stone is tossed from the top of a 210 meter building, the height of the stone as a function of time is given by h(t) = -9.8t2 – 10t + 210, where t is in seconds, and height is in meters. After how many seconds will the stone hit the ground? Round to the nearest hundredth’s place; include units in your answer. <BR>\n" );
document.write( "I got <BR>\n" );
document.write( "-10(9.8t^2 - 10t + 210)=0<BR>\n" );
document.write( "98t + 100t - 2100<BR>\n" );
document.write( "49t^2 + 50t - 1050<BR>\n" );
document.write( "t= 4.15 seconds <BR>\n" );
document.write( "Am I close?? <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=-9.8x%5E2%2B-10x%2B210+=+0 ALIGN=MIDDLE  ALT=\"-9.8x%5E2%2B-10x%2B210+=+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" );
document.write( "  <BR>\n" );
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=%28-10%29%5E2-4%2A-9.8%2A210=8332 ALIGN=MIDDLE  ALT=\"b%5E2-4ac=%28-10%29%5E2-4%2A-9.8%2A210=8332\"   DISABLED_style= \"max-width:90%; height:auto;\" >.<BR>\n" );
document.write( "  <BR>\n" );
document.write( "  Discriminant d=8332 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--10%2B-sqrt%28+8332+%29%29%2F2%5Ca ALIGN=MIDDLE  ALT=\"+x%5B12%5D+=+%28--10%2B-sqrt%28+8332+%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-%28-10%29%2Bsqrt%28+8332+%29%29%2F2%5C-9.8+=+-5.16733620703838 ALIGN=MIDDLE  ALT=\"x%5B1%5D+=+%28-%28-10%29%2Bsqrt%28+8332+%29%29%2F2%5C-9.8+=+-5.16733620703838\"   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-%28-10%29-sqrt%28+8332+%29%29%2F2%5C-9.8+=+4.14692804377307 ALIGN=MIDDLE  ALT=\"x%5B2%5D+=+%28-%28-10%29-sqrt%28+8332+%29%29%2F2%5C-9.8+=+4.14692804377307\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "    <BR>\n" );
document.write( "    Quadratic expression <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-9.8x%5E2%2B-10x%2B210 ALIGN=MIDDLE  ALT=\"-9.8x%5E2%2B-10x%2B210\"   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=-9.8x%5E2%2B-10x%2B210+=+%28x--5.16733620703838%29%2A%28x-4.14692804377307%29 ALIGN=MIDDLE  ALT=\"-9.8x%5E2%2B-10x%2B210+=+%28x--5.16733620703838%29%2A%28x-4.14692804377307%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "  Again, the answer is: -5.16733620703838, 4.14692804377307.\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+-9.8%2Ax%5E2%2B-10%2Ax%2B210+%29 ALIGN=MIDDLE  ALT=\"graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+-9.8%2Ax%5E2%2B-10%2Ax%2B210+%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ></TD></TR>\n" );
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document.write( "4.15 is the correct solution, but<BR>\n" );
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document.write( "On Earth, it's h(t) = -4.9t2 – 10t + 210, not -9.8t^2<BR>\n" );
document.write( "The -10t indicates it was thrown at 10 m/sec downward.<BR>\n" );
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document.write( "I got <BR>\n" );
document.write( "-10(9.8t^2 - 10t + 210)=0<BR>\n" );
document.write( "98t + 100t - 2100 **** you dropped the  = 0 here<BR>\n" );
document.write( "49t^2 + 50t - 1050<BR>\n" );
document.write( "--------<BR>\n" );
document.write( "Where did you get the equation with the -9.8t^2 ?<BR>\n" );
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