Well we have a function and its body is a fraction so we need to handle those edge cases, namely division by 0.
That means solving the following equation,
[tex]x^2-2x=0\implies x(x-2)\implies x_1=0,x_2=2[/tex].
As we can see x must not be equal to 0 or 2 if we do not want to end up with division by zero situation.
The domain is therefore [tex]\mathbb{R}-\{0,2\}[/tex].
Writing this as interval would be,
[tex]x\in(-\infty,0)\cup(0,2)\cup(2,\infty)[/tex].
Hope this helps.
