d-c-d.tex

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