Identify the domain and range of the function graphed below

The domain would be all real numbers such that x  4.
The range would be all real numbers such that y  0.

The domain in these problems is always the x values that can be used in the equation. As you can see in the picture, the highest number used is 4. Any number after that will produce no y value. So we know the domain must be 4 or less. 

We do the same for the y value. Since 0 is the lowest number, we know it must be greater than or equal to 0. Also, especially in graphs like this, it is important to note that even though it doesn't look like the y is growing fast, since it goes on to infinity, it will eventually get infinitely high.