Question

Which of the following represents a function?

Answer 1

It would be D or the answer with the two circles. :)

Functions have an input and an output.

Answer 2

Functions cannot have different values of y for the same value of x. Now let us check each case one at a time.

First Case: For the same value of x=-1, y has two different values of 7 and 1, which is not allowed in a function. Therefore, the first case is not a function.

Second Case: For the same value of x=-1, y has two different values of -5 and 1, which is not allowed in a function. Therefore, the second case is not a function.

Third Case: For the same value of x=3, y has two different values of 2 and 4, which is not allowed in a function. Therefore, third case is not a function.

Fourth Case: In this case no value of x is same. So, this is a function.