Since h represents the height of the ball at any given time, t, let h = 25, such that the ball will be 25m high at t.
Now, we have 25 = 20t - 5t²
5t² - 20t + 25 = 0
t² - 4t + 5 = 0
[tex]\frac{4 +- \sqrt{16 - 20}}{2}[/tex]
Since the discriminant is less than zero, there are no solutions.
Hence, the ball will never be 25m high.
