document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=186049>Question 186049</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Mr. Alim's science class launched a toy rocket from ground level with an initial upward velociy of 60 feet per second. The height h of the rocket in feet above the ground after t seconds is modeled by the equation h=60t-(16t)(16t). How long was the rocket in the air before it returned to the ground? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #139516 by </B><A HREF=/tutors/aboutme.mpl?userid=solver91311><B>solver91311(24713)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=solver91311><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=solver91311><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=139516\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <font face=\"Times New Roman\" size=\"+2\">\r<BR>\n" );
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document.write( "Your height function is incorrect.  What you have is:\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\LARGE \ \ \ \ \ \ \ \ \ \ h(t) = 60t - (16t)(16t) = 60t - 256t^2\">\r<BR>\n" );
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document.write( "The correct function, in the form you presented is:\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\LARGE \ \ \ \ \ \ \ \ \ \ h(t) = 60t - 16(t)(t)\">\r<BR>\n" );
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document.write( "Or, in a more traditional form:\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\LARGE \ \ \ \ \ \ \ \ \ \ h(t) = -16t^2 + 60t\">\r<BR>\n" );
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document.write( "Now, what you need to know is the value of <i>t</i>, different from 0 (because time 0 is when it left the ground in the first place), when the height will be zero.  So just set the right side equal to zero and solve:\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\LARGE \ \ \ \ \ \ \ \ \ \ -16t^2 + 60t = 0\">\r<BR>\n" );
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document.write( "Factor:\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\LARGE \ \ \ \ \ \ \ \ \ \ t(-16t + 60) = 0\">\r<BR>\n" );
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document.write( "Use the Zero Product Rule to get:\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\LARGE \ \ \ \ \ \ \ \ \ \ t = 0\">\r<BR>\n" );
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document.write( "Which we exclude as previously discussed, or\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\LARGE \ \ \ \ \ \ \ \ \ \ -16t + 60 = 0\">\r<BR>\n" );
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document.write( "I'll let you finish.  Remember to reduce any fractions to lowest terms.\r<BR>\n" );
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document.write( "John<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\LARGE e^{i\pi} + 1 = 0\"><BR>\n" );
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