You can put this solution on YOUR website! the domain is all real values of x that lead to a real value of f(x).
you have f(x) = 3/(x+9)
since (x+9) is in the denominator, then the denominator will be equal to 0 when x = -9.
the value of f(x) = 3/(x+9) is not defined when the denominator is equal to 0.
the domain of the function is therefore all values of x except at x = -9.
