A good answer might be:
The dot product is:
( 1.2, -4.2, 3.5 )T · ( 1.2, -4.2, 3.5 )T = 1.22 + (-4.2)2 + 3.52 = 31.33.
The unit vector is represented by:
( 1.2, -4.2, 3.5 )T /31.33. = (0.0383, -0.1341, 0.1117)T
The dot product is:
( 1.2, -4.2, 3.5 )T · ( 1.2, -4.2, 3.5 )T = 1.22 + (-4.2)2 + 3.52 = 31.33.
The unit vector is represented by:
( 1.2, -4.2, 3.5 )T /
Usually with paper-and-pencil math you should leave the answer in the first form given above (i.e. don't actually perform the division.) Often, further calculation will present an opportunity to cancel out the length if you leave it explicit.
Answer the following questions. (You might want to think of 2D vectors as you answer, although the answers will be correct for 3D vectors as well).