Question

The height of a ball in meters is modeled by f(x) = -5x^2 +36 where x is the time in seconds after the ball is hit. How long is the ball in the air?

Answer 1

`height = ground \\ height = 0 \\ f(x) = 0 \\ - 5x {}^(2) + 36 = 0 \\ 5x {}^(2) = 36 \\ {x}^(2) = (36)/(5) \\ x = + \sqrt{ (36)/(5) } = √(7.2) ≅2.683 \: sec`