Sadie is solving the following problem:

"A tennis ball is launched directly upward at 64 feet per second from a hilltop with an elevation of 75 feet. How long will it take the ball to reach its maximum height?"

After substituting known values into the equation $\displaystyle{h}=-{16}{{t}}^{{2}}+{v}_{{o}}{t}+{h}_{{o}}\usepackage{cmbright}\Huge\$ , she completed the square and put the equation in vertex form: $\displaystyle{h}=-{16}{{\left({t}-{2}\right)}}^{{2}}+{139}\usepackage{cmbright}\Huge\$ .

What can she conclude?