Tell whether the set of ordered pairs satisfies a linear function. Explain. { (1, 1), (3, 5), (5, 9), (7, 13) }?

If the rate of increase of this fraction: y/x, is constant, then the ordered pairs satisfy a "linear" function. Thus, if the change in y divided by the change in x in the set mentioned is the same between any two pairs, then the function is said to be linear. For example, from (1,1) to (3, 5), the change is [5 - 1] / [3 - 1] = 4/2 = 2. And, between (3, 5) and (7, 13), the change is [13 - 5] / [ 7 - 3] = 8/4 = 2. Since 2 = 2, in this case, we can say the function is linear.

Note: I suspect you actually "do" understand. You're probably looking for answers to a potential test question. My guess, anyway.