f(x) =The denominator must not be 0 -9x² + 27x + 36 ≠ 0 -9(x² - 3x - 4) ≠ 0 -9(x-4)(x+1) ≠ 0 x - 4 ≠ 0; x + 1 ≠ 0 x ≠ 4; x ≠ -1 The graph looks like this: There is no point where x=-1 because there is a vertical asymptote there, and there is a hole in the curve, and therefore no point at (4,- ), where the little circle is. So -1 and 4 are excluded from the domain. The domain is (- ,-1) U (-1,4) U (4, ) Edwin