Let f(x,y)=ln(xy)f(x,y) = \ln(xy)f(x,y)=ln(xy) be defined for x,y>0x, y > 0x,y>0. What is the partial derivative fxf_xfx?
1x\frac{1}{x}x1
1y\frac{1}{y}y1
1xy\frac{1}{xy}xy1
yx\frac{y}{x}xy