document.write( "Question 398198: A ball is thrown straight upward at an initial speed of 104 feet per seconds. From Physics it is known that, after t seconds, the ball reaches a height h feet given by the formula h=-16t^2 + 104 t.\r
\n" ); document.write( "\n" ); document.write( "1.The ball reaches the height of 64.96 feet after t1= _____ and t2=_____ seconds (with t1 < t2)\r
\n" ); document.write( "\n" ); document.write( "I set up the problem as 64.96= -16t^2+104t. I solved for t and I keep coming up with t1= .777 and t2= 5.222. What am I doing wrong?
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Algebra.Com's Answer #282143 by stanbon(75887)\"\" \"About 
You can put this solution on YOUR website!
A ball is thrown straight upward at an initial speed of 104 feet per seconds. From Physics it is known that, after t seconds, the ball reaches a height h feet given by the formula h=-16t^2 + 104 t.
\n" ); document.write( "1.The ball reaches the height of 64.96 feet after t1= _____ and t2=_____ seconds (with t1 < t2)
\n" ); document.write( "Solve: -16t^2+104t-64.96 = 0
\n" ); document.write( "t = [-104 +- sqrt(104^2 -4*-16*-64.96)]/(2*-16)
\n" ); document.write( "---
\n" ); document.write( "t = [-104 +- sqrt(6658)]/-32\r
\n" ); document.write( "\n" ); document.write( "t = [-104 +- 81.6]/(-32)
\n" ); document.write( "t = 5.8 seconds or to = 0.7 seconds
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.
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