document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1030926>Question 1030926</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I used the equation, y=-6x^2+36x to model the flight of hitting a tennis ball. The problem asked when was the ball exactly 48 feet off the ground. I used the x-box to find that after two seconds after being hit, the ball was exactly 48 feet off the ground. Unfortunately, I only solved half of the problem because the ball will reach 48 feet again before it hit the ground. Please help. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #645670 by </B><A HREF=/tutors/aboutme.mpl?userid=ikleyn><B>ikleyn(52781)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ikleyn><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=ikleyn><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=645670\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> .<BR>\n" );
document.write( "It would be good if you explain\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "1. What are the variables \"y\" and \"x\" in your equation. Is \"x\" the time or the horizontal coordinate? \r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "2. What is the source of this equation? Where did you take it? Where is it came from?\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "I am asking because if \"x\" is the time and \"y\" is the height above the ground in feet  (as I can conclude from your text), <BR>\n" );
document.write( "then the equation is INCORRECT.<BR>\n" );
document.write( "------------------------------------------------\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "<U>Comment from student</U>: x is the time and y is the feet above the ground and I got this from a test where I have to correct it.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "------------------------------------------------\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "<U>My responce</U>:  Then the first term in the right side of the equation y = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-6x%5E2 ALIGN=MIDDLE  ALT=\"-6x%5E2\"   DISABLED_style= \"max-width:90%; height:auto;\" > + . . . should be <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-16x%5E2 ALIGN=MIDDLE  ALT=\"-16x%5E2\"   DISABLED_style= \"max-width:90%; height:auto;\" > instead of <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-6x%5E2 ALIGN=MIDDLE  ALT=\"-6x%5E2\"   DISABLED_style= \"max-width:90%; height:auto;\" >.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );