Functions

Let $f: \mathbf{R} \rightarrow \mathbf{R}$ be the function defined by

$$ f(x)= \begin{cases}x^2-4 x-5 & \text { if } x \geq 1, \\ 2 x & \text { if } x<1 .\end{cases} $$

Which one of the following statements is TRUE?