Find the partial derivative fxf_xfx for f(x,y)=ln(x+y)f(x, y) = \ln(x+y)f(x,y)=ln(x+y).
1x+y\frac{1}{x+y}x+y1
1x\frac{1}{x}x1
1y\frac{1}{y}y1
ln(x)\ln(x)ln(x)