Which of these describes $f : \mathbb{R} - \{0\} \to \mathbb{R} - \{0\}$, $f(x) = \frac{1}{x}$?

Explanation

1. 01

   $\frac{1}{a} = \frac{1}{b}$ gives $a = b$: one-one.

2. 02

   Any non-zero $y$ is $f\left(\frac{1}{y}\right)$: onto.