Just need 40 and 54 from the pictures... Also write how did you did them

\fChapter 4 Functions of Two Variables Business Calculus 211 For problems 36 through 41, find fax, fly , foy and f for the function given. Confirm that f ny = fix. 36. f(x, y)= x -52 37. f(x, y)=x* +4x y - 6x y? - 4xy' + y+ 38. f(x, y) = 5x2y2 39. f (x, y ) = extby 40. f(x, y)= In(xy + 2x -6y) 41. f(x, y) = x 1 4 - 5