Pre-calc function

[litz]

i was wondering, it says use interval notation to describe the domain of the real function, but a real function means the domain is a set of real numbers. does it mean all real numbers? i graphed it on my calculator and got [-9,10] but i have no idea if i should have negative infinity to positive infinity for all real numbers??

f(x)=square root of (x squared -3x+2). whats the domain!?

 

[Tom Mattson]

Start small. Consider the function $f(x)=\sqrt{x}$. If the function is to be real-valued, then what sort of numbers aren't we allowed to put in for x?