You are able to move the blue line by clicking on and moving point J.

- Which axis is the blue line crossing? At what point is the blue line crossing this axis?
- Move the red slider to 1 and write the name and coordinates of the point that appears. Do the same by moving the slider to 2,3, and 4.
- What do you notice about the coordinates of these points?
- Using the answers from the above questions, make a guess as to what the equation of this line is. Move slider 2 over to check your answer.
- Move slider 2back to the left. Use point J to move the line along the axis. Stop at any point and write the equation of the point you stopped at along with the equation of this line. Check your answer by moving the blue slider.
- Use any combination of two points that lie on the line to find
the slope using the slope formula (y
_{2}-y_{1})/(x_{2}-x_{1}). Make a conclusion about the equation of horizontal lines and their slopes.

Athena Matherly, November 10, 2006, Created with GeoGebra

Please direct questions and comments to HCPS Mathematics Specialist Henrico County Public Schools, 2009