document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=455273>Question 455273</A>: <I><SPAN STYLE=\"word-break: break-all;\"> If a ball is thrown upwards at 20 ft/sec, the height h after t seconds is given by h = -16t^2 + 20t. &#8232;&#8232;How many seconds does it take for the ball to reach its maximum height, and what is this height? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #312659 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=312659\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> If a ball is thrown upwards at 20 ft/sec, the height h after t seconds is given by h = -16t^2 + 20t. &#8232;&#8232;How many seconds does it take for the ball to reach its maximum height, and what is this height?<BR>\n" );
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document.write( "The max ht is the vertex of the parabola<BR>\n" );
document.write( "The line of symmetry is t = -b/2a = -20/-32<BR>\n" );
document.write( "t = 5/8 seconds to reach max ht<BR>\n" );
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document.write( "h(5/8) = -16*(5/8)^2 + 20*5/8<BR>\n" );
document.write( "= -400/64 + 100/8 = 400/8<BR>\n" );
document.write( "Max ht = 50 feet<BR>\n" );
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