Determine the mixed second-order partial derivative fxyf_{xy}fxy for the function f(x,y)=yxf(x,y) = \frac{y}{x}f(x,y)=xy.
−1x2-\frac{1}{x^2}−x21
1x2\frac{1}{x^2}x21
−yx2-\frac{y}{x^2}−x2y
0