document.write( "Question 445089: Fireworks are shot upward with an intial velocity of 125 feet per second from a paltform 3 feet abouve the ground. use the model h= -16t squared + vt + s to find how long it will take the rocket to hit the ground? \n" ); document.write( "

Algebra.Com's Answer #306775 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

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Fireworks are shot upward with an intial velocity of 125 feet per second from a platform 3 feet abouve the ground.
\n" ); document.write( " Use the model h = -16t squared + vt + s to find how long it will take the rocket to hit the ground?
\n" ); document.write( ":
\n" ); document.write( "In this problem: v = 125, s = 3, h = 0, (h = 0 when it hits the ground)
\n" ); document.write( ":
\n" ); document.write( "-16t^2 + 125t + 3 = 0
\n" ); document.write( "Use the quadratic formula to solve this:
\n" ); document.write( " $\"x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+\"$
\n" ); document.write( "In this equation: x=t; a=-16, b=125, c=3
\n" ); document.write( " $\"t+=+%28-125+%2B-+sqrt%28125%5E2-4%2A-16%2A3+%29%29%2F%282%2A-16%29+\"$
\n" ); document.write( ":
\n" ); document.write( " $\"t+=+%28-125+%2B-+sqrt%2815625-%28-192%29+%29%29%2F%28-32%29+\"$
\n" ); document.write( ":
\n" ); document.write( " $\"t+=+%28-125+%2B-+sqrt%2815625+%2B+192+%29%29%2F%28-32%29+\"$
\n" ); document.write( ":
\n" ); document.write( " $\"t+=+%28-125+%2B-+sqrt%2815817%29%29%2F%28-32%29+\"$
\n" ); document.write( "Two solutions
\n" ); document.write( " $\"t+=+%28-125+%2B+125.765655%29%2F%28-32%29+\"$
\n" ); document.write( " $\"t+=+%28.765655%29%2F%28-32%29+\"$
\n" ); document.write( "t = -.023926
\n" ); document.write( "and
\n" ); document.write( " $\"t+=+%28-125+-+125.765655%29%2F%28-32%29+\"$
\n" ); document.write( " $\"t+=+%28-250.765655%29%2F%28-32%29+\"$
\n" ); document.write( "t = +7.8364 sec, the reasonable solution, for the rocket to hit the ground \n" ); document.write( "

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