\(\newcommand{\twoline}[2]{\begin{pmatrix}#1 \\ #2 \end{pmatrix}}\newcommand{\amp}{&}\)

The following functions all have [math] as both their domain and codomain. For each, determine whether it is (only) injective, (only) surjective, bijective, or neither injective nor surjective.
  1. [math]
  2. [math]
  3. [math]
  4. [math]

Solution: