[tex]\bf ~~~~~~~~~~~~\textit{quadratic formula}
\\\\
\begin{array}{lcccl} y=& -4.9 t^2& +20t& +10\\
&\uparrow &\uparrow &\uparrow \\
&a&b&c
\end{array}
\qquad \qquad
t= \cfrac{ - b \pm \sqrt { b^2 -4 a c}}{2 a}
\\\\\\
t=\cfrac{-20\pm\sqrt{20^2-4(-4.9)(10)}}{2(-4.9)}\implies
t=\cfrac{-20\pm\sqrt{400+196}}{-9.8}
\\\\\\
t=\cfrac{-20\pm\sqrt{596}}{-9.8}\implies t=\cfrac{20\mp\sqrt{596}}{9.8}\implies t\approx
\begin{cases}
-0.4503174725\\
4.53195012566
\end{cases}[/tex]
