Find the critical points of the function f(x) = x³ + ¹/5x² + 50x + 7. Use the First Derivative Test to determine whether the critical point is a local minimum or local maximum (or neither). (Use symbolic notation and fractions where needed. Give your answers in the form of comma separated lists. Enter DNE if there are no critical points.) f has local a minimum at f has a local maximum at Find the intervals on which the given function is increasing or decreasing. (Use symbolic notation and fractions where needed. Give your answers as intervals in the form (*, *). Use the symbol ∞ for infinity, U for combining intervals, and an appropriate type of parentheses "(",")", "[", or "]" depending on whether the interval is open or closed.) the function is increasing on