Graphs

Point-Slope Form

To write a function in point-slope form, use any two points to determine the slope. Next, substitute the slope and one of the points into the point-slope formula Point1 .

Example Find the function rule for the graph using the point-slope form.

Point2

Step 1. Choose any two points to find slope. (0, 3) & (1, 1).

Point3

Step 2. Pick any point on the line for (x1, y1).

(2, -1)

Step 3. Substitute the values for (x1, y1) and m into y - y1 = m(x - x1) to create the function rule.

y - (-1) = -2(x -2)

y + 1 = -2(x - 2)