document.write( "Question 730246: A ball is thrown upward from the top of a building. The ball's height above the ground after t seconds is given by the function: h(t) = -16t^2 + 48t +32. \r
\n" ); document.write( "\n" ); document.write( "a. What is the initial height (i.e. the height of the building)?
\n" ); document.write( "b. How high did the ball go?
\n" ); document.write( "c. When does the ball hit the ground?
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Algebra.Com's Answer #446587 by josmiceli(19441)\"\" \"About 
You can put this solution on YOUR website!
\"+h%28t%29+=+-16t%5E2+%2B+48t+%2B+32+\"
\n" ); document.write( "(a)
\n" ); document.write( "The instant the ball is thrown upward is
\n" ); document.write( "called \"+t+=+0+\". Plug this value into the equation.
\n" ); document.write( "\"+h%280%29+\" is the height of the building.
\n" ); document.write( "\"+h%280%29+=+-16%2A0+%2B+48%2A0+%2B+32+\"
\n" ); document.write( "\"+h%280%29+=+32+\" ft
\n" ); document.write( "(b)
\n" ); document.write( "The path of the ball is a parabola. The t-coordinate
\n" ); document.write( "of the vertex is at \"+t%5Bv%5D+=+-b%2F%282a%29+\" when the form
\n" ); document.write( "is like the given equation
\n" ); document.write( "\"+a+=+-16+\"
\n" ); document.write( "\"+b+=+48+\"
\n" ); document.write( "\"+-b%2F%282a%29+=+-48%2F%28+2%2A%28-16%29%29+\"
\n" ); document.write( "\"++t%5Bv%5D+=+3%2F2+\"
\n" ); document.write( "Plug this back into equation to find \"+h%5Bv%5D+\"
\n" ); document.write( "\"+h%5Bv%5D+=+-16%2A%283%2F2%29%5E2+%2B+48%2A%283%2F2%29+%2B+32+\"
\n" ); document.write( "\"+h%5Bv%5D+=+-36+%2B+72+%2B+32+\"
\n" ); document.write( "\"+h%5Bv%5D+=+68+\"
\n" ); document.write( "The max height is 68 ft
\n" ); document.write( "(c)
\n" ); document.write( "The height is zero when it hits the ground, so
\n" ); document.write( "\"+0+=+-16t%5E2+%2B+48t+%2B+32+\"
\n" ); document.write( "\"+-t%5E2+%2B+3t+%2B+2+=+0+\"
\n" ); document.write( "Use the quadratic formula
\n" ); document.write( "\"+t+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+\"
\n" ); document.write( "\"+a+=+-1+\"
\n" ); document.write( "\"+b+=+3+\"
\n" ); document.write( "\"+c+=+2+\"
\n" ); document.write( "\"+t+=+%28-3+%2B-+sqrt%28+3%5E2-4%2A%28-1%29%2A2+%29%29%2F%282%2A%28-1%29%29+\"
\n" ); document.write( "\"+t+=+%28-3+%2B-+sqrt%28+17+%29%29%2F%28-2%29%29+\"
\n" ); document.write( "\"+t+=+%28+3+%2B+sqrt%2817%29%29+%2F+2+\"
\n" ); document.write( "\"+t+=+%28+3+%2B+4.123+%29+%2F+2+\"
\n" ); document.write( "\"+t+=+3.562+\"
\n" ); document.write( "The ball hits the ground in 3.562 sec
\n" ); document.write( "---------------------------------
\n" ); document.write( "Here's the plot of the equation:
\n" ); document.write( "\"+graph%28+400%2C+400%2C+-1%2C+5%2C+-5%2C+75%2C+-16x%5E2+%2B+48x+%2B+32%29+\"\r
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