Step-by-step explanation:
I'm not sure what the square root method is, but I'm assuming that you factor.
This is how I would solve it:
[tex]h = - 16 {t}^{2} + 36 \\ 0 = - 16 {t}^{2} + 36 \\ 0 = - 4(4 {t}^{2} - 9) \\ 0 = (2t - 3)(2t + 3) \\ t = \frac{3}{2} \\ t = - \frac{3}{2} [/tex]
Since time can't be negative, you rule out the -3/2.
Answer:
[tex]t = \frac{3}{2}[/tex]