Domain & Range
Even Functions
All even functions will have similar shaped graphs, meaning they will either open upwards or downwards. Depending on the direction they open, the range will either have an absolute minimum or maximum just like quadratic functions. The range can be determined by finding the absolute maximum or minimum of the graph.
Example Find the range of y = -x4 + 4.
Step 1. Make a graph of the function.
Step 2. Determine the absolute maximum or minimum.
Since this graph is opening down, there is an absolute maximum. In this case the vertex is the point (0, 4).
Step 3. Write the range of the function.
The range of the function is all numbers less than and including 4. In set notation: 
.
*Note: Sometimes there are restrictions put on the domain, the values of x. If this is the case, plug in the minimum and maximum values of x to determine the range.