Next question Find the open intervals where the function f x 4x 24x 165x 7 is concave upward or concave downward Find any inflection points Select the correct choice below and if necessary fill in the answer box to complete your choice OA The function has a point of inflection at Type an ordered pair using integers or fractions Simplify your answer Use a comma to separate answers as needed OB The function does not have an inflection point Select the correct choice below and if necessary fill in the answer box to complete your choice OA The function is concave upward on the interval s Type your answer in interval notation Use integers or fractions for any numbers in the expression Simplify your answer Use a comma to separate answers as needed OB The function is never concave upward Select the correct choice below and if necessary fill in the answer box to complete your choice OA The function is concave downward on the interval s Type your answer in interval notation Use integers or fractions for any numbers in the expression Simplify your answer Use a comma to separate answers as needed OB The function is never concave downward