5. (7 marks) Suppose f(.7:) = 2:133 + b32: 4c where (1,!) and c are real constants. Suppose that f has a horizontal tangent line at cc = 2, and that the tangent line to f at :1: = O is given by y = 8:): + 4. Use the given information to find all possible values for (1,5. and c. Explain your reasoning