∑(X--X平)(Y--Y平)= ∑(XY--X平Y--XY平+X平Y平)= ∑XY--X平∑Y--Y平∑X+nX平Y平= ∑XY--nX平Y平--nX平Y平+nX平Y平=∑XY--nX平Y平; 2、∑(X --X平)^2= ∑(X^2--2XX平+X平^2)= ∑X^2--2nX平^2+nX平^2=∑X^2--nX平^2; 3、Y=kX+b k=((XY)平--X平*Y平)/((X^2)平--(X平)^2), b=Y平--kX平; X平=1/n∑Xi, (XY)平=1/n∑XiYi