# Homework Help: Open map

1. Nov 9, 2011

### Ted123

What is an example of a continuous function $f:\mathbb{R}\to\mathbb{R}$ such that $f(\mathbb{R})$ is open?

2. Nov 9, 2011

### CompuChip

Well, $\mathbb{R}$ is open in $\mathbb{R}$, right?

3. Nov 9, 2011

### Ted123

So $f(x)=x$ is open