Understanding Cross Product: A Refresher for 3(A x B) Calculation

Thread starter camino
Start date Sep 22, 2009
Tags

Cross Cross product Product

Sep 22, 2009

camino

Homework Statement

I simply forget how to cross product if you have:

3(A x B)

Would it be 3A x B

or

A x B then take that result and multiply by 3?

Physics news on Phys.org

Scientist returns to microbial roots and discovers potential quantum computing advancement
Physicists achieve record precision in measuring proton-to-electron mass ratio with H₂⁺
Quantum calculations provide a sharper image of subatomic stress

Sep 22, 2009

rock.freak667

Homework Helper

r(axb) = (ra)xb = ax(rb)

I believe it works like that for r=constant.

Sep 22, 2009

camino

Thank you that was my original thought.

Thread 'Finding the nth roots of a complex number'

There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...

View full post »

Thread 'Solve this problem that involves induction'

Hello, This is the attachment, the steps to solution are pretty clear. I guess there is a mistake on the highlighted part that prompts this thread. Ought to be ##3^{n+1} (n+2)-6## and not ##3^n(n+2)-6##. Unless i missed something, on another note, i find the first method (induction) better than second one (method of differences).

View full post »