# If #A= <-5 ,-4 ,-7 ># and #B= <2 ,-9 ,8 >#, what is #A*B -||A|| ||B||#?

##### 1 Answer

Jun 21, 2018

#### Explanation:

To answer this question we need three pieces:

#A*B# #||A||# #||B||#

but don't worry, they're all easy to compute!

#A*B# is the**scalar product**of two vectors. As the name suggests, it is a number (scalar), computed as follows:#A# and#B# must have the same length, and we must add the products of the coordinates of#A# and#B# in the same positions.

So, if

So, in your case, we have

The other pieces, **norm** of

We're finally ready!