Study lines in the number plane. Consider the gradient and y-intercept and relate them to the equation of the line.
Explore the effect of translation. Compare the two forms of the equation of a line.

- Drag either of the blue points on the line.
- The resulting change in the line depends on the constraint setting:
- None
- The points may be dragged anywhere, redefining the line,
- X
- The x coordinate of each point is fixed, so movement is only up or down,
- Y
- The y coordinate of each point is fixed, so movement is only left or right,
- X + Y
- The point moves only along the current line.
- Clicking and dragging the line itself allows translation of the line.
- If
*Intercepts*is selected, the X and Y intercepts are shown in green. - Values are shown as fractions or decimals according to the state of the
*Decimals*setting. - The equation of the current line is constantly displayed and updated
as points are moved. Alternatively it can be entered using the
*Enter equation…*dialog in either standard form, i.e.*x - 2y + 4 = 0*or in gradient-intercept form, i.e.*y = 1/2x + 2*. - Click and hold the chart background to bring up a magnifier.