document.write( "Question 80621: A rocket is launched straight up into the air from the ground with an initial speed of 64 ft/s. The height of the rocket (in feet) is given by the equation: h = 16t squared + 64t, where t is the time in seconds after launch. Find the time(s)when the rocket is at the ground level. \n" ); document.write( "

Algebra.Com's Answer #57939 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

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A rocket is launched straight up into the air from the ground with an initial speed of 64 ft/s. The height of the rocket (in feet) is given by the equation: h = 16t squared + 64t, where t is the time in seconds after launch. Find the time(s)when the rocket is at the ground level.
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\n" ); document.write( "I think the equation should be h = -16x^2 + 64t (gravity is pulling it down)
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\n" ); document.write( "At ground level h = 0, so we have:
\n" ); document.write( ":
\n" ); document.write( "-16t^2 + 64t = 0
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\n" ); document.write( "Factor out -16t and you have:
\n" ); document.write( "-16t(t - 4) = 0
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\n" ); document.write( "t = 0 when it starts
\n" ); document.write( "and
\n" ); document.write( "t = +4 secs when it lands \n" ); document.write( "

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