$$\vcenter {\offinterlineskip
\def \cc#1{ \hfil #1 \hfil }
\halign {
\tvg \cc {$#$}& #\tv & \cc {$#$} & \cc {$#$}& \cc {$#$}&
\cc {$#$}& \cc {$#$}& \cc {$#$}& \cc{$#$} &#\tv\cr
\noalign {\hrule}
x&& 0&& 2&& 4&&+\infty&
\cr
\noalign {\hrule}
f'(x)&&& +& 0& - & \doublevrule & -&&
\cr
\noalign {\hrule}
\buuucenter {$f(x)$} &&\down{1} &\bbrightuuparrow & \bbuup {$e^3$}
&\bbrightddownarrow ~-\infty &\doublevrule &\bbuup{$+\infty$}
~~ \bbrightddownarrow &\down{8}&
\cr
\noalign {\hrule}
}}
$$