If f(x,y)=ln(x2+y)f(x,y) = \ln(x^2 + y)f(x,y)=ln(x2+y), what is the partial derivative fyf_yfy?
1x2+y\frac{1}{x^2 + y}x2+y1
2xx2+y\frac{2x}{x^2 + y}x2+y2x
1y\frac{1}{y}y1
2x+1x2+y\frac{2x+1}{x^2+y}x2+y2x+1