estion 8 of 16 Find the critical point(s) of the function f(x) = x +x 3 + 3. (Give your answer in the form of a comma-separated list of values. Express numbers in exact form. Use symbolic notation and fractions where needed. Enter DNE if the function has no critical points.) critical point(s): Determine the x-coordinates of the critical point(s) that correspond(s) to a local minimum or a local maximum. (Give your answer in the form of a comma-separated list. Express numbers in exact form. Use symbolic notation and fractions where needed. Enter DNE if the function has no local minimum or local maximum.) local minima at x = local maxima at x =