2.11.17 Function extreme

Condition: Using level lines, find the largest and smallest values ​​of the function \( f(x, y) \) in the domain of definition of the function \( g(x, y) \). \[ f(x, y)=x^{2}-y^{2}, \quad g(x, y)=\sqrt{4-x^{2}-4 y^{2}} \]