Question

If `A= <-2 ,-5 ,4 >` and `B= <3 ,4 ,-8 >`, what is `A*B -||A|| ||B||`?

Answer 1

`-121.285`

Explanation:

`A*B=(-2)(3)+(-5)(4)+(4)(-8)`

`=-58`

`||A||=sqrt(2^2+5^2+4^2)=sqrt45`

`||B||=sqrt(3^2+4^2+8^2)=sqrt89`

`therefore A*B-||A||||B||=-58-sqrt(45xx89)`

`=-121.285`