document.write( "Question 312206: a model rocket is shot into the air and its path is apporoximated by h=-5t^2 + 30t, where h is the height of the rocket above the ground in metres and t is the elapsed time in seconds. When will the rocket hit the ground and what is the maximum height of the rocket. \n" ); document.write( "
Algebra.Com's Answer #223215 by nerdybill(7384)\"\" \"About 
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a model rocket is shot into the air and its path is apporoximated by h=-5t^2 + 30t, where h is the height of the rocket above the ground in metres and t is the elapsed time in seconds. When will the rocket hit the ground and what is the maximum height of the rocket.
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\n" ); document.write( "To find out when it will hit the ground, set h to zero and solve for t:
\n" ); document.write( "h=-5t^2 + 30t
\n" ); document.write( "0=-5t^2 + 30t
\n" ); document.write( "0=-5t(t - 5)
\n" ); document.write( "t = {0, 5}
\n" ); document.write( "We can throw out the 0 because this is when it was first launched. Therefore:
\n" ); document.write( "rocket will hit the ground in 5 seconds
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\n" ); document.write( "To find max height, find the \"axis of symmetry\":
\n" ); document.write( "x = -b/2a
\n" ); document.write( "x = -30/2(-5)
\n" ); document.write( "x = -30/(-10)
\n" ); document.write( "x = 3 sec
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\n" ); document.write( "Plug above into equation to find height:
\n" ); document.write( "h=-5t^2 + 30t
\n" ); document.write( "h=-5*3^2 + 30(3)
\n" ); document.write( "h=-5*9 + 30(3)
\n" ); document.write( "h=-45 + 90
\n" ); document.write( "h= 45 feet\r
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