## GRAPHS AND CHARTS

When looking at relationships between variables, the formula tells it all. Very often, however, a picture is indeed worth a thousand words in “giving us a feeling” for what the formula is telling us.

We will often be presented with a graph that we’ll study to gain some insight into the information the graph is presenting. Conversely, we will often need to be able to create a graph to show a formula that we are interested in. I’ll take this latter approach first.

Let’s start with a simple formula:

у = 27,000 – 2,000x.

This formula gives us a value for the variable у when we give it a value for the variable x. These variables might stand for the depreciation of a car’s value, the interest on a loan, the number of years that you will hold a loan, and so on.

Before I draw a graph...

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