Coordinate Plane Question [Whats the deal with Rise/Run?]

[PN03]

Hi, I have this issue I need to resolve. I am following this Manhattan GMAT book which gives me a few examples on how to find the slope for 2 given points on a plane.

Of course as you know the method involves one point - the other. So for example if you have a plane [2,-3] and [6,5] you would minus each with their respective axis [5-(-3) = 8 and 6-2=4] Put that in Rise(y)/Run(x) and you get 8/4 = 2. Thats great but how do I know its not the other way around? Why is it not -3-5 and 2-6 instead? I figured you take away from the righter point of the slope at first, but in a later example the book takes away from the lefter point of the slope? Is their any hard and fast rule on which point I am suppose to subtract from?

[cristofer]

it doesn't matter if you do
[5-(-3)]/[6-2] =8/4 = 2
or if you do
[-3-5]/[2-6] = -8/-4 = 2.
you'll get the same answer because pos/pos = neg/neg = pos, (and pos/neg = neg/pos = neg for other problems.) So in short, no, there is no rule as to which point you are supposed to subtract first. It simply doesn't matter

(just be consistent in which coordinates you subtract, that is, don't do something like [5-(-3)]/[2-6] where you mix up the order!)

[PN03]

Hah! thanks for clearing that up cristofer! I suspected that as one of the method but it seemed too good to be true.