document.write( "Question 479900: The height(in feet) of a firework t seconds after it is launched is given by H(t) = 3+180t-16t^
\n" ); document.write( "A. the firework is to explode at a height of at least 450 ft.
\n" ); document.write( "B. Draw a graph of the height of the firework over time, indicating the times when the firwork is at a height of at least 450 feet. \n" ); document.write( "
Algebra.Com's Answer #328783 by ankor@dixie-net.com(22740)\"\" \"About 
You can put this solution on YOUR website!
The height(in feet) of a firework t seconds after it is launched is given by H(t) = 3+180t-16t^
\n" ); document.write( "A. the firework is to explode at a height of at least 450 ft.
\n" ); document.write( "B. Draw a graph of the height of the firework over time, indicating the times when the firework is at a height of at least 450 feet.
\n" ); document.write( ":
\n" ); document.write( "Find the times when the device is at 450 ft
\n" ); document.write( "-16t^2 + 180t + 3 = 450
\n" ); document.write( "-16t^2 + 180t + 3 -450 = 0
\n" ); document.write( "-16t^2 + 180t - 447 = 0
\n" ); document.write( "Use the quadratic formula to find t; a=-16, b=180. c=-447
\n" ); document.write( "You should find the device will be at 450 ft: t ~ 3.7 sec and 7.55 sec
\n" ); document.write( ":
\n" ); document.write( "The graph of the equation -16t^2 + 180t + 3; where y axis is the height
\n" ); document.write( "\"+graph%28+300%2C+200%2C+-6%2C+20%2C+-200%2C+600%2C+-16x%5E2%2B180x%2B3%2C+450%29+\"
\n" ); document.write( "the green line is at 450 ft \n" ); document.write( "
\n" );