You were given a sample of size containing a response variable y and predictors x, =1,2,..,. Let y be a 1 vector the values for response variable, and X be a matrix containing the values for each predictor. Assume that the first predictor takes the value of 1 for every observation. Lastly, assume that the response variable y is linearly related to the predictors.

A. Write out the least-squares minimization problem in matrix form:

B. Write out the first order conditions, and derive the closed-form solution, in matrix notation.