how would i figure out the domain and range of a graph?

[aiza]

sorry if this is a dumb question, but i'm confused on how to find the domain/range of a graph. what is the difference between # < x < # and just x < #, and how would i know if a graph's domain is all real numbers? i was taught this in december and didn't have to worry about the topic until it started showing up again on my test reviews

 

[Otis]

how to find the domain/range of a graph…
how would i know if a graph's domain is all real numbers?

Hi aiza. Are you asking about finding the domain and range from a provided graph?

If the graph indicates that it continues forever to the right and left (no solid circle at either endpoint), and, if there are no gaps within the graph, then it covers all x values, so the domain would be all Real numbers.

The difference between the intervals #<x<# and x<# is that the first interval contains only values in-between the two numbers, whereas the second interval contains all values to the left of the number (on the x-axis).

The interval -10 < x < 10 contains all numbers in-between -10 and 10. A common way to show on a graph that -10 and 10 are not included in the domain is to plot open circles at each end of the graph (that is, on the curve or line at the endpoints x=-10 and x=10).

The interval x < 10 contains all numbers to the left of 10 (in other words, all numbers smaller than 10), so that interval goes forever to the left of 10.

Perhaps, you could post one or two example exercises, along with your work or thoughts, and we could go from there.



[imath]\;[/imath]

 

[Steven G]

You can think of x<# as \(\displaystyle -\infty\) < x < #.
Similarly you can think of x># as #<x<\(\displaystyle \infty\).

 

[Deleted member 4993]

sorry if this is a dumb question, but i'm confused on how to find the domain/range of a graph. what is the difference between # < x < # and just x < #, and how would i know if a graph's domain is all real numbers? i was taught this in december and didn't have to worry about the topic until it started showing up again on my test reviews

Do a Google search with key words

range and domain of a function​

You'll find several videos explaining the topic above . I would suggest that first learn the definitions of range and domain of functions.