(b) Show that the matrix X always has full column-rank, i.e., its columns are always linearly independent, regardless of the columns of X. Hence argue that the ridge regression estimate is always unique, for any matrix of predictors X. (c) Write out an explicit formula for Bridge involving X, y, A. Conclude that for any a 6 RP, the estimate aT ridge is a linear function of . y (d) N ow consider the estimation of GTE\