# Interval/Continuous/Injective/Monotonous/Exercise

Let be a real interval and let

denote a continuous injective function. Show that is strictly increasing

or strictly decreasing.Let ${}I$ be a real interval and let

- $f\colon I\longrightarrow \mathbb {R}$

denote a continuous injective function. Show that ${}f$ is strictly increasing

or strictly decreasing.