yt = β0 + β1xt + β2xt-1 + β3xt-2 + β4zt-1 + ut
1) True, false, explain: OLS estimates of the β coefficients of this model will be biased if xt is correlated with xt-1
2) True, false, explain: OLS estimates of the β coefficients of this model will be biased if xt-1 is correlated with ut.