Mrs. Agriesti's Algebra I Notes
5.1 & 5.2 Write Equations of Lines Given the Slope and a Point
Objective:
To use the slope and any point on the line to find the equation of the line.
Notes:
Steps to finding the equation:
 Write "y = mx + b".
 Find the slope by looking at the graphed line and counting the rise and run. (For help see section 4.4).
 Replace the variable m with the slope you found in step 2.
 Locate a point on the graphed line. Make note of its coordinates.
 Replace the variable x with the xcoordinate of the point from step 4 and y with the ycoordinate of the point.
 Solve for the only variable you have left, b.
 Write "y = mx + b" again.
 Replace m with the slope and b with the value you found in step 6.
Examples:
Solve:

 Write the equation of the line that passes through (8,3) with slope 4.
 Write the equation of the line that passes through (6,7) with slope 2/3.