# TASC Math Exam—Graphing Linear Functions

Some questions on the TASC Math exam involve linear functions. A linear function represents a relationship between two variables in which one variable influences the other.

In a linear function, x is usually considered to be the independent variable and y to be the dependent variable (x influences y). The independent variable (x) runs horizontally, while the dependent variable (y) runs vertically. The minimum number of points you need to construct a line is two.

The common difference of the points that describes both the steepness and direction of the line is called the slope. This is also referred to as the ratio of the rate of change in the dependent variable to the rate of change in the independent variable. The letter associated with slope is m; if m is positive, then the line rises to the right, and if m is negative, then the line falls to the right. To determine the slope of a line, you need two points: (x1, y1) and (x2, y2). Then substitute into the formula:

Slope-intercept is the most commonly used formula to represent a linear function. Just as the name implies, this formula tells you the slope (m) of the line as well as the y-intercept (b). Recall that the y-intercept is the point at which the graph crosses the y-axis.

Slope-intercept form: y = mx + b (m is the slope and b is the y-intercept)

## Practice questions

1. The equation of the line perpendicular to
2. Which line would be parallel to the line y = –3x + 4?