algebra
posted by Nilan on .
height of a projectile thrown straight up from top of 480 ft hill t seconds after bing thrown up with initial velocity vo ft/s is
h = 16t^2 +vot + 480
If vo = 96, find times when the projectile will be at a) height of 592 ft above the ground and b) crash on the ground.

so h = 16t^2 + 96t + 480
a)
you want
16t^2 + 96t + 480 = 592
t^2  6t + 7 = 0
(t7)(t+1) =0
t = 7 or a negative
b)
same thing except now you want
16t^2 + 96t + 480 = 0
solve for t, use only the positive result