Image of Element under Mapping/Examples/Image of 2 under x^4-1

Example of Image of Element under Mapping
Let $f: \R \to \R$ be the mapping defined as:


 * $\forall x \in \R: \map f x = x^4 - 1$

The image of $2$ is:


 * $\map f 2 = 15$

Proof

 * $2^4 - 1 = 16 - 1 = 15$