Use differentials to approximate the change in z for the given change in the independent variables. 2 = x2 2x5; + y Iill'hen {my} changes from (3,3) to [103,299] r:} dz = D {Type an integer er a decimal.) What are the conditions for a critical point of a function f? Choose the correct answer below. O A. The point (a,b) is an interior point of the domain of f. Either f'(a) = 0, or f' does not exist at a. O B. The point (a,b) is an interior point of the domain of f. Either f. (a,b) = 0, or f (a,b) = 0. O C. The point (a,b) is an interior point of the domain of f. Either f, (a, b) = f, (a,b) =0, or one (or both) of f, or f, does not exist at (a, b). O D. Only that f (a,b) = f (a,b)