QUESTION 2 (a). For which real number a is there a two-variable function f(x, y) such that fx = 3x2 +axy + y' and fy = 2xy + 2x2? (Hint: use Clairaut's theorem about fry and fyx.) (b). (Optional; extra credit, 5 points. ) For the value of a you found above, find a function f(x, y) such that fx = 3x2 + axy + y2 and fy = 2xy + 2x2