# Thread: Vectors and properties of cross products

1. ## Vectors and properties of cross products

The problem that I am unsure about is: k x (i - 2j). What are the rules for adding and subtracting vectors like this?

2. ## Re: Vectors and properties of cross products

The problem that I am unsure about is: K x (i - 2j). What are the rules for adding and subtracting vectors like this?
Be careful about notation, in particular capitalization.
I think you mean: $k\times(i-2j)~?$

The rules are: $\vec{a}\times(\vec{b}+\vec{c})=(\vec{a}\times\vec{ b})+(\vec{a}\times\vec{c})$ and $(\alpha\vec{ a}\times\vec{b})=\alpha(\vec{a}\times\vec{b})$

3. ## Re: Vectors and properties of cross products

Okay, I fixed it.

In that case I went through the problem like this...

= k x i + (-2)(k x j)
= j - 2i