Chapter 7 Vocabulary

outlier

A number in a set of data that is much larger or much smaller than the other numbers in the set.

unit rate

A rate with a denominator of one when simplified.

slope

A ratio that describes how steep (or flat) a line is. Slope can be positive, negative, or even zero, but a straight line has only one slope. Slope is the ratio pic or pic, sometimes written pic. When the equation of a line is written in y = mx + b form, m is the slope of the line. Some texts refer to slope as the ratio of the "rise over the run." A line has positive slope if it slopes upward from left to right on a graph, negative slope if it slopes downward from left to right, zero slope if it is horizontal, and undefined slope if it is vertical. Slope is interpreted in context as the amount of change in the y-variable for an increase of one unit in the x-variable.

central angle

An angle with its vertex at the center of a circle.

linear equation

An equation in two variables whose graph is a line. For example, y = 2.1x − 8 is a linear equation. The standard form for a linear equation is ax + by = c, where a, b, and c are constants and a and b are not both zero. Most linear equations can be written in y = mx + b form, which is more useful for determining the line's slope and y-intercept.

form

(of an association) The form of an association can be linear or non-linear. The form can contain cluster of data.

frequency table

A table that displays counts, or frequencies, of data.

simple interest

Interest paid on the principal alone.

y-intercept

The point(s) where a graph intersects the y-axis. A function has at most one y-intercept; a relation may have several. The y-intercept of a graph is important because it often represents the starting value of a quantity in a real-world situation. For example, on the graph of a tile pattern the y-intercept represents the number of tiles in Figure 0. We sometimes report the y-intercept of a graph with a coordinate pair, but since the x-coordinate is always zero, we often just give the y-coordinate of the y-intercept. For example, we might say that the y-intercept of the graph below is (0, 2), or we might just say that the y-intercept is 2. When a linear equation is written in y = mx + b form, b tells us the y-intercept of the graph. For example, the equation of the graph below is y = x + 2 and its y-intercept is 2.

lattice points

The points on a coordinate grid where the grid lines intersect. The diagram below shows two lattice points. The coordinates of lattice points are integers.

y = mx + b

When two quantities x and y have a linear relationship, that relationship can be represented with an equation in y = mx + b form. The constant m is the slope, and b is the y-intercept of the graph. For example, the graph below shows the line represented by the equation y = 2x + 3, which has a slope of 2 and a y-intercept of 3. This form of a linear equation is also called the slope-intercept form.