Determine whether each of the following is a subspace or not. Justify your answer! {(x, y, z) = R | 2x 3y + 4z = 0} - (i) W := 1 E (ii) W := {A R | adj(A) = AT }, where adj(A) denotes the adjoint matrix, and AT denotes the transpose of A R. (iii) W3 := {p(x) = P3 | P(0) 2}