document.write( "Question 200691: A ball is projected upward from ground level. After t seconds its height in feet is a function defined by f(t)= -16t2 + 48t. After how many seconds will it reach a height of 32 ft? \n" ); document.write( "

Algebra.Com's Answer #150940 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

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A ball is projected upward from ground level.
\n" ); document.write( " After t seconds its height in feet is a function defined by f(t)= -16t2 + 48t.
\n" ); document.write( " After how many seconds will it reach a height of 32 ft?
\n" ); document.write( ":
\n" ); document.write( "height h = f(t)
\n" ); document.write( ":
\n" ); document.write( "equation when height = 32:
\n" ); document.write( "-16t^2 + 48t = 32
\n" ); document.write( ":
\n" ); document.write( "-16t^2 + 48t - 32 = 0; subtract 32 from both sides
\n" ); document.write( ":
\n" ); document.write( "Simplify, divide by -16 (changes the signs)
\n" ); document.write( "-16(t^2 - 48t - 2) = 0
\n" ); document.write( ":
\n" ); document.write( "factors to:
\n" ); document.write( "(t - 2)(t - 1) = 0
\n" ); document.write( ";
\n" ); document.write( "Two solutions:
\n" ); document.write( "t = 1 sec; at 32 ft on the way up
\n" ); document.write( "and
\n" ); document.write( "t = 2 sec; at 32 ft on the way down
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( "Given equation looks like this; (t on the x axis, h on the y axis):
\n" ); document.write( " $\"+graph%28+300%2C+200%2C+-2%2C+5%2C+-10%2C+50%2C+-16x%5E2%2B48x%29+\"$ \n" ); document.write( "

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