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– SycoraxNov 22 '22 at 18:45
You have to explain some notation for your post to be fully understood; e.g. what are $x_1,y_n,\ldots$.
– utobiNov 22 '22 at 19:07
It's not correct. The duplicates give the formula to use. BTW, there appears to be a typographical error in your expression for $\tilde \beta_1:$ the numerator likely involves only $x_1+x_n.$
– whuberNov 22 '22 at 19:32