Question

(-1, 1) (1, -1) (2, -2) (-2, 2) (1, -2) is it a function?? how do I explain if it is? please help! thanks :)

Answer 1

It is not a function, because the x value 1 is assigned to more than one y value (-1 and -2)

For future reference: if each x value has only one y value, it is a function. Keep in mind though, one y value can be assigned to multiple DIFFERENT x values

Answer 2

This relation is NOT a function

Explanation:

As you see in the attached image, the x value of 1 has 2 different points assigned to it. This relation would fail the vertical line test, therefore it is not a function.

Key words:
Relation: Any graph

Function: A relation that has 1 y value for every x value

Vertical line test: An imaginary line drawn on a relation/function to test if it is a function. (in some cases, like this relation, you will see right away from the placement of the points that it is not a function)

Hope that helps