An increasing linear function results in a graph that slants upward from left to right and has a positive slope. A decreasing linear function results in a graph that slants downward from left to right and has a negative slope.

A constant linear function results in a graph that is a horizontal line The slope of a linear function can be calculated by dividing the difference between y -values by the difference in corresponding x -values of any two points on the line

linear function — a function with a constant rate of change that is a polynomial of degree 1, and whose graph is a straight line. horizontal line — a line defined by f ( x ) = b , where b is a real number. The slope of a horizontal line is 0. slope — the ratio of the change in output values to the change in input values; a measure of the steepness of a line. decreasing linear function — a function with a negative slope: If f ( x ) = m x + b , then m < 0.