f x 2 cos x 2 cos x xx 3x 7x The solution set for f x 0 in the interval 0 2x is 4 2 24 Simplify your answer Type an exact answer using as needed Use integers or fractions for any numbers in the expression Use a comma to separate answers as needed Find the solution set for f x 0 in the specified interval Choose the correct answer below OA The solution set of f x 0 is 0 OB The solution set of f x 0 is x 3x 22 3x 7x 4 2 2 OC The solution set of f x 0 is 0