se 1: Let d be a positive integer. (1) Imitate the proof of the irrationality of v2 to show that Vd is rational if and only if d is the square of an integer. (2) When d is not a square, show that Q[Vd) := {q1 + 92Vd : 91, 92 ( Q} is a field. (3) Exhibit a basis, i.e. a linearly independent spanning set, of Q[Vd] as a Q-vector space