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Key vocabulary from Chapter 4 of McDougal Littell Algebra I. This chapter covers the graphing of linear equations and functions.


the four regions into which the coordinate plane is divided by the x-axis and the y-axis

standard form of a linear equation

Ax + By = C, where A, B, and C are real numbers and A and B are BOTH not zero

linear function

the equation Ax + By = C is a ___, provided B does not equal zero


the x-coordinate of a point where a graph crosses the x-axis


the y-coordinate of a point where a graph crosses the y-axis


the ___ (m) of a nonvertical line is the ratio of the vertical change (the rise) to the horizontal change (the run) between any two points (x1,y1) and (x2,y2) on the line: m = y2 - y1 / x2 - x1

rate of change

a comparison of change in one quantity with a change in another quantity; can be represented by the slope of a line

slope-intercept form

a linear equation written in the from y = mx + b where m is the slope and b is the y-intercept of the equation's graph


two lines in the same plane that do not intersect are ___ lines

direct variation

the relationship of two variables x and y if there is a nonzero number a, such that y = ax; if y = ax, then y is said to vary directly with x

constant of variation

the nonzero constant a in a direct variation equation y = ax or in an inverse equation y = a/x

function notation

a way to name a function using the symbol f(x) instead of y; the symbol f(x) is read as "the value of f at x" or as "f of x"

family of functions

a group of functions with similar characteristics

parent linear function

the function f(x) = x, which is the most basic function in the family of linear functions

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