Theory

• $e^x$ is strictly increasing, so it is one-to-one.
• Range depends on domain:
  • If domain is $\mathbb{R}$, range is $(0,\infty)$.
  • If domain is $\mathbb{R}^+=(0,\infty)$, range is $(1,\infty)$.
• Onto depends on matching range with the chosen co-domain.