Aball is thrown upward. what is its initial vertical speed? the acceleration of gravity is 9.8 m/s^2 and maximum height is 4.3 m. neglect air resistance.. answer in units of m/s.

H = v o · t  - g t² / 2
v = v 0 - g t
0 = v o - 9.8 t
v o = 9.8 t
4.3 =  9.8 t · t - 9.8 t² / 2
4.3 = 9.8 t² - 4.9 t²
4.3 = 4.9 t²
t² = 4.3 : 4.9
t² = 0.87755
t = √ 0.87755
t = 0.93678 s
v o = 9.8 · 0.93678 
v o = 9.18 m/s

its initial vertical speed is 9.18 m/s.

What the heck i didn’t know