Question

When a football is kicked with a vertical speed of 20m/s its height h, in meters, after t seconds is given by the equation h = -5t&2 +20t

a ) how long is the football in the air

b ) how long is it kicked is the football at a height of 15 m

How am i supposed to solve this

Answer 1

I meant h= - 5^2+20t

Answer 2

a) h = 0 when the ball lands ... 0 = -5 t^2 + 20 t ... solve for t

b) is unintelligible