document.write( "Question 203756This question is from textbook
\n" ); document.write( ": An angry construction worker throws his wrench downward form a height of 128ft with an initial velocity of 32ft per second. The height of the wrench above the ground after t seconds is given by S(t)= -16t^2-32t+128. \n" ); document.write( "

Algebra.Com's Answer #153737 by Earlsdon(6294) $\"\"$ $\"About$

You can put this solution on YOUR website!
Er...what's the question?
\n" ); document.write( "Could it be that you want to know when the wrench hits the ground (or an unfortunate passer-by)?
\n" ); document.write( "Let's assume that it is!
\n" ); document.write( "Given:
\n" ); document.write( " $\"S%28t%29+=+-16t%5E2-32t%2B128\"$ the wrench hits the ground when its height, S = 0.
\n" ); document.write( " $\"0+=+-16t%5E2-32t%2B128\"$ Rearrange this to look like:
\n" ); document.write( " $\"-16t%5E2-32t%2B128+=+0\"$ Factor out a -16 to ease the calculations a bit.
\n" ); document.write( " $\"-16%28t%5E2%2B2t-8%29+=+0\"$ Note the changes in the signs! Applying the zero product rule, we get:
\n" ); document.write( " $\"t%5E2%2B2t-8+=+0\"$ Factor this quadratic equation.
\n" ); document.write( " $\"%28t-2%29%28t%2B4%29+=+0\"$ from which we get:
\n" ); document.write( " $\"t+=+2\"$ or $\"cross%28t+=+-4%29\"$ Discard the negative solution as the time, t, should be a positive value.\r
\n" ); document.write( "\n" ); document.write( "The wrench hits the ground in 2 seconds.\r
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