“…Next, we can write some equalities and inequalities, using several results from Section 2, related to variance, covariance and the standard deviation of vectors x, y ∈ X. Therefore, from relations (8), (10), (11), (15), (18)- (20), (22), (25), we obtain the following relations: where a, b ∈ R. By dividing by u = 0, we deduce the relation a x u + be = w u , where e = u u , so e = 1. Therefore, we obtain a = ( w u , x u |e)…”