Question

If `A= <7 ,-5 ,1 >` and `B= <4 ,1 ,3 >`, what is `A*B -||A|| ||B||`?

Answer 1

`sqrt26 (sqrt 26 - sqrt 75)`

Explanation:

`A.B= 7*4 +(-5)*1 +1*3`=26

`||A||= sqrt (7^2 + (-5)^2 + 1^2)= sqrt75`

`||B||= sqrt (4^2 +1^2 +3^2)= sqrt 26`

The given expression would therefore equal to `26-sqrt75 sqrt26`

=`sqrt26 (sqrt 26 - sqrt 75)`