- $ D = \\\mathbb{R}\\\backslash \\\left\\\{ 2 \\\right\\\}$
- $ D = \\\mathbb{R}\\\backslash \\\left\\\{ { \\\pm 2} \\\right\\\}$
- $ D = \\\mathbb{R}\\\backslash \\\left\\\{ { - 1;2} \\\right\\\}$
- $ D = \\\mathbb{R}\\\backslash \\\left\\\{ { - 1; \\\pm 2} \\\right\\\}$