3. Let the population ("true") model bey = Bo + BiX1 + B2x2 + B3X3 + u. This model satisfies the four MLR assumptions. Nonetheless, you estimate a model that omits X3. Let Bo, B1, and B2 be the estimators from a regression of y on x, and X2. Show that the expected value of B, is E( B1) = B1+ B3 Zi=1ri Xi3 Where mu are the residuals from the regression of x1 (dependent variable) on X2 (independent variable). Hints: You'll need the following information - B1 = Llerfuyi Substitute for yi where yi = Bo + B1X1 + 82x2 + 83X3 + uj. Then do some algebra and take the expectation of the expression treating X;3 and my and nonrandom. Keep in mind that E(ui) = 0