1. (2,4)
2. (-∞, -5)
3. (-9, ∞)
I think I am over-thinking it
Well it's not clear what you're being asked to find, but if you just need to verbally describe the interval, I'd go with:
1. $\displaystyle x \in (2,4)$ means x is a real number between 2 and 4 exclusive.
2. ...a real number less than -5.
3. ...a real number greater than -9.
These are not ordered pairs! Interval notation provide just another way to indicate a range of numbers. Brackets mean "including", and parentheses mean "not including". You can also rewrite intervals as compound inequalities.
Take a look:
$\displaystyle (a, b)$ is $\displaystyle a < x < b$
$\displaystyle [a, b]$ is $\displaystyle a \le x \le b$
$\displaystyle (a, b]$ is $\displaystyle a < x \le b$
$\displaystyle [a, b)$ is $\displaystyle a \le x < b$
$\displaystyle (-\infty, c)$ is $\displaystyle x < c$
$\displaystyle (-\infty, c]$ is $\displaystyle x \le c$
$\displaystyle (c, \infty)$ is $\displaystyle x > c$
$\displaystyle [c, \infty)$ is $\displaystyle x \ge c$
We never use brackets next to infinity or negative infinity.
Now try rewriting your intervals as inequalities.
I don't have a scanner but I send you to the link of the piece of paper. Its a PDF file. I am 100% it is not a bad photocopy/print-out.
Here is the link. Page 3.
http://susd.desertmountain.schoolfus...682007b4f66e36