This week we started our graphing and linear relations unit. One of the main things we learned was domain and range. The domain is all of the coordinates that the graph covers, and the range is all of the coordinates that are covered.

Domain and range can be shown in “curly brackets” such as in the following example.

{x|-4 ≤ x ≤ 7, x ∈ R}

Sometimes if the graph just contains a bunch of points, the domain and range can be given in specific numbers,

ex. D = {-2,0,1,4,7} or R = {1,3,4,9,12}

here’s what one of those graphs could look like:

But they can also be lines meaning their points can be anywhere on those lines,

ex. D = {x|-2 ≤ x ≤ 7, x ∈ R} or {y|1 ≤ y ≤ 12, y ∈ R}

here’s what one of those graphs could look like:

They can also be a line, but have no beginning and/or end. This graph would have lines with arrows to represent that it continues on.

ex {x|x ∈ R} or {y| y ≤ 12, y ∈ R}

here’s what one of those graphs could look like:

When writing in these curly brackets, especially with line graphs, you need to form a “sentence”. You start with the axis you are talking about (x/y), then the possible points, and then finish with x ∈ R or y ∈ R, which means x/y is an element of a real number.