The magnitude of vector v is and the same direction as .

Let is unite vector of u.

         (Write unit vector form in the direction of u)

           (Substitute )

                      (simplify)

                 (simplify)

Since the above vector has magnitude one and points in the direction of u, we can just multiply it by 3 and we will have a vector of magnitude 3.

Thus, .

Let check this magnitude as follows:

The magnitude of vector v is .

                                 (Apply magnitude formula: )

        (Substitute )

                      (Simplify)

                                (Simplify)

                                             (Simplify)

The unit vector is .