\"\"

\

The expression of the curve is \"\".

\

The level curves for \"\" belongs to the family of functions \"\".

\

\"\"

\

Let \"\".

\

\"\"

\

Graph :

\

Graph the function \"\" for different values of \"\".

\

\"\"

\

\"\"

\

Graph the function \"\" for different values of \"\".

\

\"\".