 #1
 258
 39
 Homework Statement:

(Choose all options below that correctly complete the following sentence.)
The domain of a multivariable function z=f(x,y) is:
a subset of the real numbers
a union of two subsets of the real numbers
a subset of the xyplane
the union of the set of all values x where f(x,y) exists with the set of all values where f(x,y) exists
the set of all ordered pairs of points (x,y) so that f(x,y) exists

 Relevant Equations:
 I think that only the last definition is complete: "the set of all ordered pairs of points (x,y) so that f(x,y) exists"
E.g. all real numbers could be a domain but not necessarily, etc. Am I right?