Answer:
The x which is not in the domain of the function is the root of the denominator
6) x+3=0, x=-3 is the x which is not in the domain of the function
7) |2x+5|=0, x=-5/2 is the x which is not in the domain of the function
8) x^2-16=0, x=±4 are the x which are not in the domain of the function
