*World of Mathematics*. ©2005-2006 Thomson Gale, a part of the Thomson Corporation. All rights reserved.

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In order to set the stage for a **definition** of combined variation, we will first discuss some of the more basic types of variation. A quantity y is said to vary directly as x if y=kx, where k is a constant, called the constant of variation. In this case, we also say that y is directly proportional to x; so we also call k the constant of proportionality. This means that as x gets larger, so does y; and as x gets smaller, so does y. We may also have y varying directly as some power of x. For example, if y=kx^{2}, then we would say that y varies directly as the **square** of x. If y=k/x, where k is a constant, we say that y varies inversely as x, or that y is inversely proportional to x. If y varies inversely as x...

This section contains 584 words(approx. 2 pages at 300 words per page) |