Question
Let $A = \{x \mid x \in \mathbb{R},\ x \text{ is not a positive integer}\}$. Define $f: A \rightarrow \mathbb{R}$ as $f(x) = \frac{2^x}{x - 1}$, then $f$ is
Let $A = \{x \mid x \in \mathbb{R},\ x \text{ is not a positive integer}\}$. Define $f: A \rightarrow \mathbb{R}$ as $f(x) = \frac{2^x}{x - 1}$, then $f$ is