I(x, y) = [ (2t + 1) esint dt + x Consider the function defined by - ( f(x, y) = xy(x-y x + y + 1 (2 0 (2t - 1) tan (t) dt (x, y) = (0,0) (x, y) = (0,0) (a) (8pt) Find f(x, y) and fy(x, y) for (x, y) = (0,0). (b) (2pt) Use the limit definition of partial derivatives to find f(0, 0) and fy(0,0). (c) (6pt) Use the limit definition of partial derivative to find fry (0,0) and fyr (0,0).