Parallel Vectors and Dot Product Calculations

[g.lemaitre]

Homework Statement

Homework Equations

The Attempt at a Solution

I can't get the answer above. Is u -4 over 15? if so, the dot product of u and x should be
-20 + 105. I'm clearly on the wrong track.

 

[E_M_C]

If you're going to do it that way, notice that the 1/5 term in the unit vector u should be multiplied by both -4 and 3 before it is dotted with x.

 

[g.lemaitre]

Thanks, I was able to figure it out by looking at the next example.