A group of students launches a model rocket from the top of a building. The
students have determined the equation y= − ;
(x+ 6)(x− 18) to describe the
<
height of the rocket above ground level, y, in meters, at any time, x, in seconds. when tree =0, 2,4,6,8,10,12,14,16and 18 so what Height above ground y
when x=0 (i.e. at the time of launch):
y = -(0+6)(0-18) = -6*-18 = 108 meters
When x=2:
y = -(2+6)(2-18) = -8*-16 = 128 meters
When x=4:
y = -(4+6)(4-18) = -10*-14 = 140 meters
When x=6:
y = -(6+6)(6-18) = -12*-8 = 96 meters
When x=8:
y = -(8+6)(8-18) = -14*-4 = 56 meters
When x=10:
y = -(10+6)(10-18) = -16*2 = -32 meters (below ground level)
When x=12:
y = -(12+6)(12-18) = -18*0 = 0 meters (rocket reaches maximum height and starts descending)
When x=14:
y = -(14+6)(14-18) = -20*-2 = 40 meters (rocket is descending)
When x=16:
y = -(16+6)(16-18) = -22*-4 = 88 meters (rocket is descending)
When x=18:
y = -(18+6)(18-18) = -24*-6 = 144 meters (rocket hits the ground)