 So let's find the domain and range of a relationship given as a set of ordered pairs, and then determine if the relationship is a function. So remember, definitions are the whole of mathematics, all else is commentary. The domain of a relationship is the set of allowable input values, while the range is the set of possible output values. And, since our function is given as a set of ordered pairs, remember that in that case the inputs are the x values and the outputs are the y values. So the domain is the set of inputs, that's the set of x values, which are 3, 2, 5, and 1. Meanwhile, the range is the set of output values, those are the y values, and those are 7, 5, 5 again, and 4. And since we're curving a set, we list each element only once, so our range is 7, 5, 4. Definitions are the whole of mathematics, all else is commentary. If we want to determine if the relationship is a function, it helps to remember what a function is. So our definition, a function, is a relationship where every input has one and only one output. And in this case, we see that none of the input values are repeated, and so every input has a unique output, and so f is a function. Well, let's try to do the same thing for this relationship. So again, we'll find our domain as a set of x values, 3, 2, 5, and 3 again, and since it's a set, we don't list it twice. Our range is the set of output values, 7, 5, 2, and 4. And if we look at our list carefully, we see that the input 3 has two different outputs. Here the output is 7, and here the output is 4. And since we have an input with two different outputs, this does not meet the requirement for the definition of a function, and so g is not a function.