Algebra: Chapter 12-5, p 557
Direct Variation
An equation of the form `y = kx` where `k` is a constant, expresses direct variation. `k` is called the constant of variation. Sometimes you have to solve for the constant of variation given the initial information and then use the `k` to solve additional problems given the same `k`.
Math-8: Chapter 13-1, p 664
Squares and Square Roots
Radicals are the funny looking things over the numbers. For example, the `sqrt(16) = 4` or the `sqrt(121) =11`. Perfect squares are numbers like 25, 49, and 64 because when you take the `sqrt(144)`, you get an answer that is a WHOLE NUMBER, namely 12.
Remember, that the `−sqrt(100) =−10` and that there are usually 2 roots for a square root. The `sqrt(64) = 8` or `−8`. We can also write the answer as `±8`. The positive value is called the “principal square root” and the one we use most commonly in Algebra classes.