Question

Which relation is a function?

Answer 1

B

Explanation:

For a relationship to be a function

Each value of x in the domain can only have 1 unique value of y in the range. That is, one-to-one correspondence.

The only relation which meets this criteria is B

Answer 2

The answer is option B: {(1,3);(-1,5);(2,7);(-2,7);(3,5);(-3,3)}

Explanation:

Each element is composed of a first and second point, or by an 'x' and 'y' coordinates, respectively. In this way, all x coordinate from the set of elements constitute the 'domain', and all y coordinates of the set of elements constitute the 'image'.

So, for a set of elements be a function, each point of the domain have to have one an only one image. In other words, two elements with the same image have to have a distinct x's coordinate.

If we take a look at the set of elements in the different options, we find different elements which repeat image:

1) The pairs (1,0) and (1,-1) in the set of point of option A

2) The pairs (-2,-1) and (-2,-2) in the set of point of option C

3) The pairs (1,3) and (1,3) in the set of point of option

In the set of elements of B option, all the elements with the same y coordinate have different x's coordinates.