Take the 2-minute tour ×
Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

$a\times(b\times(a\times b))=a\times((b\cdot b)a-(b\cdot a)b)=-a\cdot ba\times b$
can anyone expand on how the final answer is derived?
I try to expand but ended up scratching my head.
the best I can do is this
$a\times(ab\cdot b - ab\cdot b)$

share|improve this question

1 Answer 1

up vote 1 down vote accepted

In $a\times((b\cdot b)a-(b\cdot a)b)$, the first term is zero because $a \times a = 0$. This leaves the second term. Note that $a\cdot b = b\cdot a$.

share|improve this answer
    
$a\times-(a\cdot b)b$ but how did it end up $-a\cdot ba \times b$?we could just exchange cross and dot operator, right? –  kypronite Oct 21 '12 at 14:14
    
sorry,forget what I said.Just found out about the cross product $(cu)\times v=u\times (cv)$ –  kypronite Oct 21 '12 at 14:25

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.