Consider the set = {v1 = (1, 1, 1, 1), v2 = (2, 2, 3, 1), v3 = (1, 1, 1, 1)} in R 4 .

Show that is a basis of the subspace V = {x1 + x2 + x3 + x4 = 0} of R 4 .[Do not have to check that V is a subspace. Can use results obtained in the course to simplify your proof.] Justify your answer.