Answer: It assigns a unique output to each input.
This statement is true of all functions, including the function f(x) = 3x - 12.
A function assigns a unique output to each input, meaning that for each value of x that is input into the function, there is a corresponding and unique value of y that is output. This is also called the vertical line test, if for any vertical line cuts the graph of a function at most one time, it is a function.
It does not matter whether it is linear or nonlinear or whether the correlation is positive or negative, the statement that It assigns a unique output to each input is true for all functions.
Explanation: