# Probably easy proof for you guys

1. Jan 21, 2010

### benhou

1. The problem statement, all variables and given/known data

Prove if $$\vec{x}\times\vec{v}=\vec{x}\times \vec{u}$$, then $$\vec{v}=\vec{u}$$
where $$\vec{x}\neq \vec{0}$$

2. The attempt at a solution

Use the definition of cross product and tried to reduce it.

2. Jan 21, 2010

### LCKurtz

That is false as stated. Let x = <-2, 3, 1>, u = <1,2,3>, v = < 3,-1,2>. Then x cross u and x cross v are both <7,7,-7>. So your first step in solving the problem is to state it correctly.