document.write( "Question 620600: A model jet is fired up in the air from a 20-foot platform with an initial upward velocity of 68 feet per second. The height of the jet above the ground after t seconds is given by the equation h=-16t^2+68t+20, where h is the height of the jet in feet and t is the time in seconds since it is launched. What is the maximum height the jet reaches, to the nearest foot. \n" ); document.write( "
Algebra.Com's Answer #390278 by Alan3354(69443)\"\" \"About 
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A model jet is fired up in the air from a 20-foot platform with an initial upward velocity of 68 feet per second. The height of the jet above the ground after t seconds is given by the equation h=-16t^2+68t+20, where h is the height of the jet in feet and t is the time in seconds since it is launched. What is the maximum height the jet reaches, to the nearest foot.
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\n" ); document.write( "The simplest way to do this is to find the times when h = 20
\n" ); document.write( "One is t = 0, at the start.
\n" ); document.write( "h=-16t^2+68t+20 = 20
\n" ); document.write( "-16t^2+68t = 0
\n" ); document.write( "t = 0
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\n" ); document.write( "-16t + 68 = 0
\n" ); document.write( "t = 68/16 = 4.25 seconds
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\n" ); document.write( "t at apogee = 1/2 that since it takes the same time to ascend as to descend
\n" ); document.write( "t = 2.125 seconds
\n" ); document.write( "Sub 2.125 for t to find max height.
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