$$x=[x_1,x_2];\ y=[y_1,y_2]$$ $$f=\left(\frac{x_2}{x_2+y_2}\right)^2\sqrt{\frac{x_1}{x_1+y_1}}$$ Find a point where $y$ is at a maximum and $x$ is at a minimum.
This problem is very simple but I cannot remember the exact way to solve it? Thanks a lot :)