???????

(1 point) \[ f(x)=3 \tan x, \quad \text { on }(-\pi, \pi) \] a) Find the first and second derivatives. \[ \begin{array}{l} f^{\prime}(x)= \\ f^{\prime \prime}(x)= \end{array} \] b) Identify the graph that displays \( f \) in blue and \( f^{\prime \prime} \) in red. c) Using the graphs of \( f \) and \( f^{\prime \prime} \), indicate where \( f \) is concave up and concave down. Give your answer in the form of an interval. NOTE: When using interval notation in WeBWork, remember that: You use 'INF' for \( \infty \) and '-INF' for \( -\infty \). And use 'U' for the union symbol. Enter DNE if an answer does not exist. \( f \) is concave up on \( f \) is concave down on