Let f(x) = - 0.5 . x4 + 3x2. Use a graphing calculator (like Desmos ) to graph the function f. a. Determine the interval(s) of the domain over which f has positive concavity (or the graph is "concave up"). Preview b. Determine the interval(s) of the domain over which f has negative concavity (or the graph is "concave down"). Preview c. Determine any inflection points for the function. If there is more than one, enter all of them as a comma-separated list. Preview Submit