PP4) The following sets are described in set-builder notation. Express them in roster notation: 1. $\left\{x Vin \mathbb {N} \mid \frac{125}{x} \in \mathbb{N} ight\}$. 2. $\left\{x Vin \mathbb{R} \mid x^{2}+x+1=8 ight\}$. 3. $\left\{x Vin \mathbb {N} \mid x^{2}