Hi I'm working on this OLS regression model problem I have started the question by calculating the b1 estimator but I have a different identity to the one used in the model answers, which I have also attached below. How do I derive what they have in the model question? enter image description here

The model answer

  • $\begingroup$ what have you tried? also consider adding the 'self-study' tag. $\endgroup$
    – utobi
    Dec 23, 2022 at 17:14