document.write( "Question 479546: A ball is thrown vertically upward at a velocity of 15 feet per second from a bridge that is 55 feet above the level of the water. The height h, in feet, of the ball above the water at the time t in seconds after it is thrown is
\n" ); document.write( "h = 16t^2 + 20t - 48
\n" ); document.write( "Find the time when the ball strikes the water \n" ); document.write( "
Algebra.Com's Answer #328579 by lwsshak3(11628)\"\" \"About 
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A ball is thrown vertically upward at a velocity of 15 feet per second from a bridge that is 55 feet above the level of the water. The height h, in feet, of the ball above the water at the time t in seconds after it is thrown is
\n" ); document.write( "h = 16t^2 + 20t - 48
\n" ); document.write( "Find the time when the ball strikes the water.
\n" ); document.write( "**
\n" ); document.write( "When the ball strikes the water, its height above the water=0
\n" ); document.write( "h = 16t^2 + 20t - 48=0
\n" ); document.write( "solve by quadratic formula as follows:
\n" ); document.write( "..
\n" ); document.write( " \"x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+\"
\n" ); document.write( "..
\n" ); document.write( "a=16, b=20, c=-48
\n" ); document.write( "t=[-20ħsqrt(400-4*16*-48)]2*16
\n" ); document.write( "t=[-20ħ√3472]/32
\n" ); document.write( "t=(-20ħ58.92)/32
\n" ); document.write( "t=1.22 sec
\n" ); document.write( "or
\n" ); document.write( "t=-2.47 sec (reject,t>0)
\n" ); document.write( "ans:
\n" ); document.write( "The ball strikes the water 1.22 sec after it is thrown \n" ); document.write( "
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