f(x)=4x-x^3(A) Use interval notation to indicate where f(x) is concave up.Concave up:(B) Use interval notation to indicate where f(x) is concave down.Concave down:(C) Find all infection points of f. If there are no inflection points, enter -1000. If there are more than one, enter them separated by comInflection point(s) at x =
