Problem
6. Ulysses throws a football to an open wide receiver. The path of the ball can be modeled by the function \( f(x)=-6 t(t-5) \). How long is the ball in the air?
Solution
Step 1 ：\( f(t)=-6 t(t-5) \)
Step 2 ：\( f(t) = 0 \) when \( t=0 \) or \( t=5 \)
Step 3 ：The ball is in the air for 5 seconds.
