Step 1: set the radican = to 0, to find the marking points for your interval of values on the number line.
step2: here we have 3 region of possibilities,namely (negative infinity to -1), (-1 t0 1), and (1 to positive infinity).
step 3: Pick testing points for each interval and substitute into the original ftn to see if it satisfies the ftn. If it does, then that region is your possibles values of X, thus your domain.
step 4: domian for the ftn is: (negative infinity to -1), and (1 to positive infinity),the graph does not exist when X is between -1 and 1.