Determine whether the statement is true or false. Justify your answer.
1. If u and v have the same magnitude and direction, then u and v are equivalent.
2. If u is a unit vector in the direction of v, then v = ∥v∥u.
3. If v = ai + bj = 0, then a = −b.
4. If u = ai + bj is a unit vector, then a2 + b2 = 1.