# What does this domain mean?

• August 13th 2009, 06:44 PM
chengbin
What does this domain mean?
http://i31.tinypic.com/2crua0w.jpg

What does this circled symbol mean?
• August 13th 2009, 06:54 PM
pickslides
It means x is an element of the real numbers.
• August 13th 2009, 07:04 PM
chengbin
How do you type that in latex?
• August 13th 2009, 07:20 PM
pickslides
Try "x \in R" wrapped in math tags, this will produce $x \in R$
• August 13th 2009, 08:11 PM
Gamma
Generally it should be written in math blackboard font, as $x \in \mathbb{R}$ in LaTeX and it will look like $x\in \mathbb{R}$. On these forums you need to wrap in in math tags, like pickslides mentioned.
• August 13th 2009, 11:30 PM
QM deFuturo
How would you read the entire first line out loud (labeled (3) )?

In the algebra book I'm using, it uses a colon ":" for "such that", whereas here I think the vertical bar is being used as "such that" in the set notation.
• August 13th 2009, 11:37 PM
Gamma
"f sends x to the square root of the quantity x+3, where the domain is: The set of all x such that x is greater than or equal to -3, and x is an element of the real numbers."

| and : are both common notations for such that in sets.