how to tell if function has domain of "all real numbers" when looking at graph

[reillyyy0327]

how to tell if function has domain of "all real numbers" when looking at graph

how do you tell if a function has a domain of "all real numbers" when looking at a graph?

 

[ksdhart2]

Okay, so let's say you have some unknown function y=f(x). Your question is, then, how do you determine if the domain of y=f(x) is all real numbers, given only the graph, correct? If that's the case, think about the definition of the domain of a function. The domain is the set of all numbers that function can accept as inputs. So, in your function y=f(x), which variable corresponds to the domain? Based on that, what would you expect to see on the graph if the domain was all real numbers? Or to phrase it a different way, what would you expect to see on the graph if the domain was not all real numbers?