The max value can be found by setting the derivative equal to 0 and solving for x, then subbing that value for x back into the original function and solving for y.
![f'(x)= ((x^2+3)(0)-2(2x))/((x^2+3)^2)](https://img.qammunity.org/2019/formulas/mathematics/high-school/oc49hijkyattbuilp0gr1u0jopzaozd2i5.png)
which simplifies to
![f'(x)= (-4x)/((x^2+3)^2)](https://img.qammunity.org/2019/formulas/mathematics/high-school/zff19uyv87gb85eohvfyg6mn6e89svxrpq.png)
. This derivative is equal to 0 when -4x is equal to 0. If -4x = 0, then x = 0. If we find f(0), then
![f(0)= (2)/((0)^2+3)](https://img.qammunity.org/2019/formulas/mathematics/high-school/rp4nj5obqypxglzmtrl6d40qxubh3e4zdf.png)
and y here is 2/3. So the max value occurs at (0, 2/3). There you go!