8. BONUS The logistic sigmoid function is defined as et o ( x) = 1 + ex What is the inverse function, o (x)? Given a data set D = {(Xn, yn), n = 1,..., N), where yn E (0, 1), logistic regression uses the model p(y = 1/x) = o(0 x+b). Assuming the data are iid, find the derivative of the log-likelihood with respect to Or [10 poin