document.write( "Question 88620: Develop a height equation: A ball thrown upward from the roof of a building 100m tall with an initial velocity of 20m/s. When will the ball reach a height of 80m? \n" ); document.write( "

Algebra.Com's Answer #64428 by Nate(3500) $\"\"$ $\"About$

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$\"f%28x%29+=+%28-1%2F2%29gx%5E2+%2B+vx+%2B+h\"$
\n" ); document.write( "f(x) determines height after x seconds
\n" ); document.write( "g is the gravitational constant
\n" ); document.write( "v is the initial velocity
\n" ); document.write( "h is the initial height
\n" ); document.write( " $\"80+=+%28-1%2F2%2932x%5E2+%2B+20x+%2B+100\"$
\n" ); document.write( " $\"-20+=+-16x%5E2+%2B+20x\"$
\n" ); document.write( " $\"5%2F4+=+x%5E2+-+5x%2F4%29\"$
\n" ); document.write( " $\"105%2F64+=+80%2F64+%2B+25%2F64+=+5%2F4+%2B+25%2F64+=+%28x+-+5%2F8%29%5E2\"$
\n" ); document.write( " $\"0+%2B-+sqrt%28105%29%2F8+=+x+-+5%2F8\"$
\n" ); document.write( " $\"%285+%2B-+sqrt%28105%29%29%2F8+=+x\"$
\n" ); document.write( "After $\"%285+%2B+sqrt%28105%29%29%2F8\"$ seconds, the ball would be 80m high.
\n" ); document.write( " $\"graph%28300%2C400%2C-3%2C4%2C-20%2C120%2C80%2C-16x%5E2+%2B+20x+%2B+100%29\"$ \n" ); document.write( "

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