Question

If `A= <2 ,6 ,-3 >` and `B= <-6 ,-4 ,4 >`, what is `A*B -||A|| ||B||`?

Answer 1

`-48 - 14sqrt(17)`

Explanation:

`a = (2,6,-3) => |a| = sqrt(2^2+6^2+(-3)^2) = 7`

`b = (-6,-4,4) => |b| = sqrt((-6)^2+(-4)^2+4^2) = 2sqrt(17)`

`a*b = (2,6,-3)*(-6,-4,4) = -12-24-12=-48`

`a*b - |a||b| = -48 - 14sqrt(17)`