document.write( "Question 31848This question is from textbook
\n" ); document.write( ": An object is projected upward from the top of a tower. Its distance in feet above the ground after t seconds is given by s(t)=-16t^2+64t+80. How many seconds will it take to reach ground level? \n" ); document.write( "

Algebra.Com's Answer #18417 by stanbon(75887) $\"\"$ $\"About$

You can put this solution on YOUR website!
When it reaches ground level its height above the ground will be zero.
\n" ); document.write( "So, write -16t^2+64t+80=0
\n" ); document.write( "-16(t^2-4t+5)=0
\n" ); document.write( "(t-5)(t+1)=0
\n" ); document.write( "t=5 seconds or t=-1 second
\n" ); document.write( "The answer you want is t=5 seconds
\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H. \n" ); document.write( "

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