Apr 11, 2017

Domain: possible x values (left to right)
Range: possible y values( down to up)

#### Explanation:

The domain is all the possible X Values.
Think if you were to drag your pencil right or left are there points where the graphs stops. At times you will have a domain that extends to infinity, you can have a domain like $\left(- \infty , \infty\right)$

The range is all the possible Y values, as if moving your pencil up and down.

With domains and ranges there is also certain notation. The range for this would be $\left(- \infty , \infty\right)$ notice the parentheses since these are not part of the graph they are moving towards that value.

The domain would be $\left(- \infty , 2\right) U \left(2 , \infty\right)$: All of these are parentheses since at an asymptote the value is never actually reached. We need to break the domain at 2 since the graph does not include 2 because of the asymptote.

An example with hard brackets would be a square root function where all of the values need to be + inside for example $\sqrt{x}$. The domain is $\left[0 , \infty\right)$ including ) since the graph will have this point. The range will also be $\left(0 , \infty\right)$.