Determine the second partial derivative fxyf_{xy}fxy for f(x,y)=sin(xy)f(x, y) = \sin(xy)f(x,y)=sin(xy).
cos(xy)\cos(xy)cos(xy)
cos(xy)−xysin(xy)\cos(xy) - xy\sin(xy)cos(xy)−xysin(xy)
sin(xy)+xycos(xy)\sin(xy) + xy\cos(xy)sin(xy)+xycos(xy)
−xysin(xy)-xy\sin(xy)−xysin(xy)