Test 3 Q2 For the function f(x) = 325 5x4 – 1 determine the following (show all your work): a) f'(:) b) The x value(s) where f(x) has a horizontal tangent line. c) The intervals where f(a) is increasing and the intervals where f(a) is decreasing. d) f" (2). e) The intervals where f(x) is concave upwards and the intervals where f(x) is concave downwards.