[tex] V(x) [/tex] would not be a function. A function is a relation between [tex] x [/tex] and [tex] y [/tex], where a selected x-value will always equal one y-value. This means that a selected [tex] x [/tex] cannot map to two y-values at the same time, which occurs with the x-value 5 in [tex] V(x) [/tex].
