How do you find the domain of a function?

Question

Like...... f(x)=x^2-2
and
g(x)=5x+4

Answer 1

that problem is almost like slope-intercept form. domain is written like this n

Answer 2

Both of those functions include all real numbers in their domains.
Some functions use a square root or cubic root of x.
Then you can only include positive numbers in the domain.
When dividing by x, zero cannot equal x.
Wikipedia has more information on domains of functions.