5. Find the relative maxima of f (x) = cos? (3x) on the interval (0, 4.189) by applying the First Derivative Test. Round numerical values in your answer to three decimal places. A) relative maxima: (0.524, 1), (1.571, 1), (2.618, 1), (3.665,1) B) relative maxima: (0.524, 0), (1.571, 0), (2.618, 0), (3.665,0) C) relative maxima: (0.524, 1), (1.047, 1), (1.571, 1) D) relative maxima: (1.047, 1), (2.094, 1), (3.142, 1) E) relative maxima: (2.094, 1), (2.618, 1), (3.142, 1) 6. Find the open interval(s) on which f (x) =-7x2 + 70x +8 is increasing or decreasing. A) increasing on (-0o, 5); decreasing on (5, 00) B) increasing on (-co, 10); decreasing on (10, co) C) increasing on (-0o, 1 12); decreasing on (112,co) D) increasing on (-00, 40); decreasing on (40, co) E) increasing on (-00, 16); decreasing on (16,co) 7. Identify the open intervals on which the function y = 20x -40 cosx, 0