Answer
$x=1$ ($\lim\limits_{x \to 1} f(x)\not=f(1)$)
$x=2$ ($\lim\limits_{x \to 2} f(x)$ doesn't exist)
$x=3$ ($f$ is undefined)
Work Step by Step
The function has discontinuities in the points:
$x=1$
$x=2$
$x=3$
In the point $x=1$, $\lim\limits_{x \to 1} f(x)\not=f(1)$, therefore Condition 3 is violated..
In the point $x=2$, $\lim\limits_{x \to 2} f(x)$ doesn't exist, therefore Condition 2 is violated
In the point $x=3$, the function is undefined, therefore Condition 1 is violated.
