Vector equation of a line vs. Slope-Intercept equation of a line. Notice how the[i] direction vector[/i] determines the slope (same numbers) and that the [i]direction vector[/i] does not have to be [b]on[/b] the line. Notice how the [i]position vector[/i] u is not required to be an [i]axis intercept[/i], it can point anywhere in 2D or 3D