Question 3 [4]: In the simple linear regression model Yi = Bo + Bidi + er, i = 1,..., n, the residuals are defined by ei = Yi - (Bo + Bitz). Here Bo and B1 are least squares estimates that satisfy the equations n n Cri = nBo + BI Eri i=1 i=1 n n [Yixi = Bo Exit BI Ex?. i=1 i=1 i=1 Given the above two equations, show that n n Ce = Erei = 0. i=1 i=1