Restate the Question.
We must find B such that the given relation is a function. We can draw the following diagram
Answer the question.
The relation f will be a function if B is different from 2 and 4, for instance B could be equal to 6.
Check you answer.
If we choose B=6, we have the following picture:
which correspond to the graph of a function.
Explain your reasoning.
If B is equal to 2 (or 4), the relation is not a function because there are two elements in the domain (X) which correspond to 2 differents values on the range (Y). For instance, if we choose B=2, we have
which doesn't corresponds to a graph of a function.