c3 range and domain?

I understand what range and domain IS, but I can never work it out unless I'm given the graph. How exactly do you do it? I know it's only worth one mark so should be pretty easy but I just can't grasp it.

It might've been a better idea to post this in the maths forum
The Domain is what you can put into a function.
e.g. $f(x) = \sqrt{x}$ - can only have positive (real) values of x.
Therefore the domain is $x \geq 0$

The range is what you can get out of a function.
e.g. $f(x) = x^2$
Here any real x will always give a positive number or 0.
So the range is $f(x) \geq 0$

Hope that makes sense

OK thanks, I think I got it!
And it says I am in the maths forum...

The range is what you can get out of a function.
e.g. $f(x) = x^2$
Here any real x will always give a positive number or 0.
So the range is $f(x) \geq 0$

I understand what range and domain IS, but I can never work it out unless I'm given the graph. How exactly do you do it? I know it's only worth one mark so should be pretty easy but I just can't grasp it.

Surely this is only the case if the domain is $x \in \mathbb{R}$? Which wasn't stated.