In Example 2, change (2,−1) to (−2, 1).

Data from Example 2

Find the equation of the line through (2,−1) and (6, 2). We first find the slope of the line through these points:

Then by using either of the two known points and Eq. (21.6), we can find the equation of the line (see Fig. 21.17):

m = 2- (-1) 6-2 || 3 4