The domain of the function is just what values of x is the function true. For the first one you would write x=4, 8, 12 because there are only three values. Since the functions stops at 12 on the graph it is discrete. It stops. It does not continue
The next one we need more values in between for the domain. We start at 0 and end at 6. So our values are 0, 6 and everything in between. 0
