Consider the function f(x, y) = (y - 2x). (a) Draw the level curves of this function for levels c = 0, 1, 2. Please clearly label each level curve with the appropriate value of c. (b) Use the previous answer to sketch the graph z = = f(x, y). (c) Find all first and second order derivatives of this function. (Please label all your derivatives clearly.) (d) Find the equation of the tangent plane to z = f(x, y) at (x, y) = (2, 1).