A good answer might be:

u · v · w makes no sense. If u · v = a (a scalar), then a · w makes no sense. If v · w = b (a scalar), then u · b makes no sense. Either way the original expression makes no sense.

Review of Dot Product Properties

It would be good to review the properties of the dot product.

Definition of dot product u · v

Commutivity of dot product u · v

Dot product of orthogonal u · v

0 · 0

a (u · v)

| v |²

u · (v + w )

(v + w ) · u

0 · u

QUESTION 8:

(Trick Question: ) What is 0 · u ?

Definition of dot product u · v
Commutivity of dot product u · v
Dot product of orthogonal u · v
0 · 0
a (u · v)
\| v \|²
u · (v + w )
(v + w ) · u
0 · u