When you are finding the slope of a line using two points, it doesn't matter which point you choose to be (x1,y1) and which point you choose to be (x2,y2)?

Typically if it is a linear function then it doesn't matter. However if it is a quadratic, cubic, and so on and so forth....() you may want to used the distance formula if you are not given any other points (with the exception of the vertex, asymptote or roots... etc).