# If A= <4, 9 ,-1 > and B= <9 ,-1 ,8 >, what is A*B -||A|| ||B||?

The answer is $19 - \sqrt{98} \cdot \sqrt{146} =$
The dot product is $\vec{A} . \vec{B} = 36 - 9 - 8 = 19$
Norm of ∥vecA∥=sqrt(16+81+1)=sqrt(98)
Norm of ∥vecB∥=sqrt(81+1+64)=sqrt(146)
So the result is =vecA.vecB-∥vecA∥*∥vecB∥=19-sqrt98*sqrt146