TeX source:

\begin{array}{l|c|c|c|l}x & f(x) & f^{\prime}(x) & f^{\prime \prime}(x) & \text { Concavity (up or down) } \\\hline 1 & + & + & - & \text { down } \\2 & + & - & - & \text { down } \\3 & - & - & + & \text { up } \\4 & - & 0 & - & \text { down }\end{array}