The equation $y = -6t^2 + 51t$ describes the height (in feet) of a projectile launched from the surface of Mars at 51 feet per second. In how many seconds will the projectile first reach 108 feet in height?
108 = -6t^2+ 51t
-6t^2+51t-108 = 0 Use Quadratic Formula a = -6 b = 51 c = -108
you will get two values of t ....one is on the way up..... the other is on the way down....