Question

Which one of the relations does not represent a function?A {(-5, -6), (-4,-2), (0, -1), (3, 2), (-4, 9)}B {(1,5), (2, 10), (3, 15), (4, 20), (5, 25), (6, 30)}C {(-3,-2), (-2,-2), (0,5), (1, 6), (4, 10)}D {(-7, 1), (-5, 1, (-1, 1), (1, 1), (8, 2)}

Answer 1

In order to have a function, we have to have a exactly one value of the dependant variable for each value of the independent variable in the domain of the function.

Then, to find the one that is not a function, we have to find a pair of values with the same independent variable and two different values for the dependant variable.

In this case, the set A is not a function:

A {(-5, -6), (-4,-2), (0, -1), (3, 2), (-4, 9)}

For x=-4, we have two values for y (y=-2 and y=9). This is not allowed by the definition of a function.

The answer is A.