Question

The following set of ordered pairs represents y as a function of x.

Answer 1

Answer:   C (-9, 8)

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Explanation:

The point (9,8) is in the original set of ordered pairs.

We cannot include (9,-8) since x = 9 is already listed. We can't have repeated x values. If x repeats, then we don't have a function.

This rules out choice A.

Choices B and D are eliminated for similar reasoning.

Choice C can be included because x = -9 hasn't been mentioned yet.

Note: A function is when any given x value leads to exactly one y value.