


Linear Equations and GraphsDetermining Linear Equations (or Functions) from Information about the LineIf we are given a straightline graph, we can find the slope m and intercept b by direct measurement, and hence write down the equation. More usually, we are given some information about the line which allows us to calculate m and b and hence write the equation for the line. A linear function can be determined in the following cases:
Example 6A.Case 1: We are given the slope and a point and asked to find the equation of the line:
Example 6B.Here we look at a special case of the above example where we are given the slope and the xintercept. As the xintercept defines a point, we again have the slope of a line and a point on the line and so we can find the linear function. Note: If we are given the slope and the yintercept, finding the equation of the line y = mx + b is straighforward as we have both m and b and can substitute these directly into the equation. Exercise 6.In the following exercise you are given the slope and one of the following: a general point on the line, the xintercept or the yintercept. Use the information given to determine the linear function. Example 7.Case 2: We are given two points and asked to find the equation of the line that goes through these two points:
Exercise 7.<< Graphing a Linear Function Using the Slope and yIntercept  Linear Equations and Graphs Index  Linear Equations >>
