f(x) = 1x−1\frac{1}{x-1}x−11 f(x) = x + 1x−3\frac{1}{x-3}x−31 f(x) = \frac{ x^{2} + 2x}{ x^{2} -1} f(x) = 2xx−3\frac{2x}{x-3}x−32x f(x) = \frac{ x^{2} + 2x}{ x^{2} +1}