# Thread: Write the following sets using interval notation?

1. ## Write the following sets using interval notation?

{xЄR | X squared>4}
{xЄR | x<0} ∩ {yЄR | y squared ≥25}
{xЄR | -5≤ x≤ 5} U {xЄR | x-10<30}

thanks

2. Originally Posted by b0mb3rz
{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 ... ?

3. Originally Posted by b0mb3rz
{xЄR | X squared>4}
{xЄR | x<0} ∩ {yЄR | y squared ≥25}
{xЄR | -5≤ x≤ 5} U {xЄR | x-10<30}

thanks
I will try

1. (-2, 2)
2. [-5.5]
3.[-5,5] U (-infinty ,20)
= [-5,20)

4. yeah thanks,
i tried the questions before hand and got some right just wanted to make sure
first week at uni so not used to lectures and stuff