6. Find all relative extrema of the function f (x) = 2x4 - 24x3 +6 Use the Second Derivative Test where applicable. no relative max or min B) relative min: (9, -4368); no relative max C) relative max: (9, 4368); no relative min D) relative max: (18, 69990) ; no relative min E) relative min: (18, 69990); no relative max 7. Determine the open intervals on which the graph of the function y = 5x - tan 3x, -2, |is concave upward or concave downward. A) concave upward: (-7,0 ; concave downward: (o, 7 ) B) concave upward: 10' 10 Concave downward: (-