Explain why the function is differentiable at the given point. f(x, y) = 4 + x ln(xy − 9), (5, 2) The partial derivatives are fx(x, y) = Correct: Your answer is correct. and fy(x, y) = Correct: Your answer is correct. , so fx(5, 2) = 10 Correct: Your answer is correct. and fy(5, 2) = 25 Correct: Your answer is correct. . Both fx and fy are continuous functions for xy > Incorrect: Your answer is incorrect. and f is differentiable at (5, 2). Find the linearization L(x, y) of f(x, y) at (5, 2). L(x, y) =