Given the function defined by f(x)=x-x-4x+4 2. (a) (b) (c) Find the zeros of f. Write an equation of the line tangent to the graph of fat x=-1. The point (a,b) is on the graph of and the line tangent to the graph at (a,b) passes through the point (0,-8) which is not on the graph of f. Find the values of a and b.