Question 121
Let $f(x) = x^2 - 6x + 5$. Draw on the plane the set of pairs $(x, y)$ that satisfy the following system of inequalities
$$
\begin{cases}
f(x) + f(y) \leq 0 \\
f(x) - f(y) \geq 0
\end{cases} .
$$
$$
\begin{cases}
f(x) + f(y) \leq 0 \\
f(x) - f(y) \geq 0
\end{cases} .
$$