Let u,v and w be vectors satisfying u∙v=3,u∙w=4,v∙w=5.
Then what are (u+2v)∙w,(w−u)∙v,(3v−2w)∙uequal to? Enter the list in the order above.
Try the method of substitution. You can put every variable in terms of another variable. For example, you could write u as 3/v, and w as 5/v. Where does that get you?
Here's my best attempt
(u +2v) * w = uw + 2vw = 4 + 2(5) = 14
(w - u) * v = wv - uv = 5 - 3 = 2
(3v - 2w) * u = 3vu - 2uw = 3(3) - 2(4) = 9 - 8 = 1
+8 
