f(x) = 2tan x, on (Jl', Jr) a) Find the first and second derivatives. w= we 4b b) Identify the graph that displays f in blue and f \" in red. B c) Using the graphs of f and f \" , 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 00 and '-|NF' for oo. And use 'U' for the union symbol. Enter DNE if an answer does not exist