Answer Happy

Find the intervals on which f is increasing and decreasing f(x) = 6 cos (3x) on [-] Select the correct choice below and, if necessary, fill in the answer box(es) to complete your choice OA. 1 is decreasing on the open interval(s) and fis increasing on the open interval(s) (Simplify your answers Use a comma to separate answers as needed. Type your answers in interval notation Type an exact answer, using as needed Use integers or tractions for any numbers in the expression) OB. 1 is increasing on the open interval(s) 1 is never decreasing (Simplity your answer. Use a comma to separate answers as needed Type your answers in interval notation Type an exact answer, using as needed Use integers or fractions for any numbers in the expression) OC. fis decreasing on the open interval(s) fis never increasing (Simplify your answer. Use a comma to separate answers as needed. Type your answers in interval notation Type an exact answer, using as needed Use integers or fractions for any numbers in the expression) OD. fis never increasing or decreasing