Domain and Range
From Math Wiki
Domain and Range
For starters, remember that domain refers to the x axis (the horizontal line), and Range to the y axis (the vertical line).
Next, if you are finding the domain and/or range for a ray or segment, the point will tell you whether it is greater than or equal to (x >), less than or equal to (x <), just plain greater than (x >), or less than (x <). If the point is a closed circle (☻) then it means it will have the "or equal to" included, but if it's an open circle (☺), it will be only the greater than, or less than. Also, domain and range can have more then one greater or less then sign in it for examlpe A<x<B which is domain A<x<B and range the same thing just with a Y in the middle of the two numbers.
Domain:
- x > = there is a closed point with an arrow pointing to the right.
- x < = there is a closed point with an arrow pointing the the left.
- x > = there is an open point with an arrow pointing to the right.
- x < = there is an open point with an arrow pointing the the left.
Range:
- y > = there is a closed point with an arrow pointing upward.
- y < = there is a closed point with an arrow pointing downward.
- y > = there is an open point with an arrow pointing upward.
- y < = there is an open point with an arrow pointing downward.
After finding the Domain and Range of lines on a graph, you are sometimes asked to make an equation for the line. Remember that inorder to do this you have to find the slope of the line which is rise over run, and then you can finish by using your domain and range to finish the equation.
If you are still having problems understanding Domain and Range,
this website will help you understand domain and range better.
