Is it possible to solve and explain this question in a different way? I am working on an online mathematics Helper web site and I need solutions in different ways. This is not a homework or any kind of exam as I already have a solution of these questions. I just need different ways of solutions so that I can write different algorithms on those solutions and then call them in software coding randomly.
given some input (from the domain) to a function, the function must return exactly one output (in the range)
Since your table has one value (8) returning 2 values (4 & 6) that table can't be describing a function.
The answer is simply applying the definition of a function.
maybe it would help you to think of it in normal "function" syntax rather than as a table.
f(4) = 2
f(12) = 3
therefore f is not a function, because a function can't return 2 answers for one input.