Economists often express their ideas using mathematical concepts and a special vocabulary. Why? Because these tools enable economists to express themselves more precisely than with ordinary language. For example, someone who has never studied economics might say, "When used textbooks are available, students won't buy new textbooks." That statement might not bother you right now. But once you've finished your first economics course, you'll be saying it something like this: "When the price of used textbooks falls, the demand curve for new textbooks shifts leftward."
Does the second statement sound strange to you? It should. First, it uses a special term—a demand curve—that you haven't yet learned. Second, it uses a mathematical concept—a shifting curve—with which you might not be familiar. But while the first statement might mean a number of different things, the second statement— as you will see in Chapter 3—can mean only one thing. By being precise, we can steer clear of unnecessary confusion. If you are worried about the special vocabulary of economics, you can relax. All of the new terms will be defined and carefully explained as you encounter them. Indeed, this textbook does not assume you have any special knowledge of economics. It is truly meant for a "first course" in the field.
But what about the math? Here, too, you can relax. While professional economists often use sophisticated mathematics to solve problems, only a little math is needed to understand basic economic principles. And virtually all of this math comes from high school algebra and geometry.
Still, you may have forgotten some of your high school math. If so, a little brushing up might be in order. This is why we have included an appendix at the end of this chapter. It covers some of the most basic concepts—such as the equation for a straight line, the concept of a slope, and the calculation of percentage changes— that you will need in this course. You may want to glance at this appendix now, just so you'll know what's there. Then, from time to time, you'll be reminded about it when you're most likely to need it.
An on-line introduction to the use of graphs can be found at http:// syllabus.syr.edu/cid/graph/book. html.
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