Question

Which relation is a function?

Answer 1

D

Explanation:

a function is a relation of two sets that associates to every number of the first set only one number of the second set. Typical examples are functions from integers to integers or from the real numbers to real numbers.

Answer 2

D. the quadratic equation

Explanation:

This is because in a function, there can not be multiple solutions for one x value. Each of the graphs display points in which the answer to x is multiple values of y, which is not a characteristic of a function.

You can see this by doing a vertical line test. Place and guide your pencil or any straight edge along the beginning of a graph to the end. If the line crosses x at two or more points, the graph is not a function. The quadratic equation is the only one that is a function because as your pencil moves along, you will see that each point has its own x value and nothing overlaps.