Linear equation y = k x + d

We concentrate on the meaning of k and d in the linear equation y = kx + d by trying different values for k and d. To do this we might enter the following lines in the input text field at the screen's bottom (press enter at the end of each line).

    k = 1
    d = 2
    y = k x + d

Now we can change k and d in the algebra window (right click: "Edit") or in the input text field

    k = 2
    k = -3
    d = 0
    d = -1

You can change k and d very easily with the arrow keys (animation, 4.1.2) or sliders (right click on k or d, Show Object; see 3.2.10).

In a similar way we might investigate the equations of conic sections such as x²/a² + y²/b² = 1, b²x² + a²y² = a²b² or (x - m)² + (y - n)² = r².