- $ \\\left\\\{ {x \\\in Z/6{x^2} - 7x + 1 = 0} \\\right\\\}$.
- $ \\\left\\\{ {x \\\in Q/{x^2} - 4x + 2 = 0} \\\right\\\}$.
- $ \\\left\\\{ {x \\\in R/{x^2} - 4x + 3 = 0} \\\right\\\}$.
- $ \\\left\\\{ {x \\\in N/\\\left| x \\\right| < 1} \\\right\\\}$.