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## Homework Statement:

- Find max or min value of function $$f(x,y)=\frac{x+y^2}{1+x^2+y^2} $$ which is defined by $$x^2+y^2=4$$

## Homework Equations:

- $$f(x,y)=\frac{x+y^2}{1+x^2+y^2} $$

First I took the partial derivatives (f'x=0 and f'y=0) and got x=-1 or 1 and y=0 but these values are outside our definition right?

I did a parameter change to trigs and got result f(0,2) is max and f(-2,0) is min. is this correct?

edit: maybe its f(1, 3) is max?

I did a parameter change to trigs and got result f(0,2) is max and f(-2,0) is min. is this correct?

edit: maybe its f(1, 3) is max?