Question

If `A= <-2 ,4 ,3 >` and `B= <3 ,2 ,-8 >`, what is `A*B -||A|| ||B||`?

Answer 1

-22-`sqrt 2233` = -22-47.25= -69.25

Explanation:

Dot product AB= (-2)(3) +42 +3(-8)= -6+8-24= -22

||A||= `sqrt(2^2 +4^2 +3^2)` = `sqrt29`

||B||= `sqrt(3^2 +2^2 +(-8)^2`= `sqrt77`

Now A*B- ||A|| ||B||= -22-`sqrt29 sqrt77`

= -22-`sqrt 2233`