Calculating Second-Order Partial Derivatives Find all the second-order partial derivatives of the functions in Exer- cises 41-50. 41. f(x, y) = x + y + xy 42. f(x, y) = sin xy 43. g(x, y) = x²y + cos y + y sin x 44. h(x, y) = xe" + y +1 46. s(x, y) = tan¹ (y/x) 48. w = ye¹²-y 50. w = x - y x² + y 45. r(x, y) = ln (x + y) 47) w = x² tan (xy) 49. w = x sin (x²y)