If you missed part 1, you should read that first. Lets look at why r-value is independent of translation and scaling from the mathematical approach.
Consider so is a scaling parameter while is a translation parameter. Notice first we can re-write the formula like this.
We finally end up with the conclusion that the r-value will have no change at all! I hope this explains why r-value is independent of scaling and translation. Do leave comments should you have other methods!