{xЄR | X squared>4}
{xЄR | x<0} ∩ {yЄR | y squared ≥25}
{xЄR | -5≤ x≤ 5} U {xЄR | x-10<30}
thanks
$\displaystyle \{x \in \mathbb{R}|x^2>4\} = (-\infty, -2) \cup (2, +\infty)$
$\displaystyle \{x \in \mathbb{R}|x<0 \} \cap \{y \in \mathbb{R}|y^2\geq 25 \} = (-\infty, -5]$
$\displaystyle \{x \in \mathbb{R}|-5 \leq x \leq 5 \} \cup \{x \in \mathbb{R}|x-10 < 30 \} = [-5, 20)$
All your questions are quite straight forward, so I'm interested to know where you have had difficulties ... ?