4. Given f (x) =x' -7x+6, find the equation of the line tangent to the graph of f ( x) at (2, -4). 5. Find all values of x at which the function at f(x) = |x -16 is NOT differentiable. Use the graph of the function to determine your conclusion. For questions #6-10, use the shortcuts for derivatives that we developed in class. No limit processes necessary! Simplify each answer in a way that is consistent with how the function is given. (Leave it the way you found it.) 6. Given at f (x) =4x' -3x' +17x-12, find at f' (x)