It x and find the equation of the line tangent to the graph of f at the indicated value of x Find the value s of x where the tangent line is horizontal f x In 12 9x 2x x 1 f x The equation of the line tangent to the graph of f at x 1 is y Select the correct choice below and fill in any answer boxes in your choice OA The value s of x where the tangent line is horizontal is are Simplify your answer Use a comma to separate answers as needed B The tangent line is never horizontal