[tex]\bf ~~~~~~~~~~~~\textit{quadratic formula}
\\\\
\begin{array}{llcccl}
& 1 x^2& +1 x& +5&=0\\
&\uparrow &\uparrow &\uparrow \\
&a&b&c
\end{array}
\qquad \qquad
x= \cfrac{ - b \pm \sqrt { b^2 -4 a c}}{2 a}
\\\\\\
x=\cfrac{-1\pm\sqrt{1^2-4(1)(5)}}{2(1)}\implies x=\cfrac{-1\pm\sqrt{-19}}{2}
\\\\\\
x=\cfrac{-1\pm\sqrt{-1\cdot 19}}{2}\implies x=\cfrac{-1\pm\sqrt{-1}\cdot \sqrt{19}}{2}
\\\\\\
x=\cfrac{-1\pm i \sqrt{19}}{2}[/tex]
