And it might look like it keeps line straight, but that's just because I'm only showing the horizontal and vertical gridlines.
它可能看起来是直线 但那只是因为我只展示水平和垂直网格线。
Linear algebra
But I showed last time how we can think about them visually as smashing around space in such a way that gridlines stay parallel and evenly spaced, and so that the origin remains fixed.