gistfile1.tex

\begin{variations}
x & \mI & & -1 & & \sqrt2 & & 3 & \\
\filet
f’(x) & \ga- & \z & + & \z & \dr+ & \bd \\
\filet
\m{f(x)} & \h1 & \d & 0 & \cb & \m{\frac{1}{4}} & \ch & \h\pI & \bd \\
\end{variations}