Well, i am taking a first course in elementary statistics, so we do not actually prove anything at all. So i was wonderign how does one determine the line of best fit? y=mx+b, where m is the slope of the line of best fit, I know that the slope is equal to m=SS(xy)/SS(x), where SS(x) is the sum of square of x, while SS(xy) the sum of the squares of x,y. also b=[SUM(y)-m*SUM(x)]/n but i have no idea how one would come up with these expressions. Can somebody show a proof for this, or just point me to the right direction?