If $A= <8 ,1 ,-1 >$ and $B= <-2 ,4 ,3 >$ , what is $A*B -||A|| ||B||$ ?

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Answer 1 · 2017-01-28T06:36:42

The answer is $=-58.75$

Let 's start by calculating the dot product

$vecA.vecB=<8,1,-1>.<-2,4,3>$

$=-16+4-3=-15$

The modulus of $vecA$

$=||vecA||=||<8,1,-1>||=sqrt(64+1+1)=sqrt66$

The modulus of $vecB$

$=||vecB||=||<-2,4,3>||=sqrt(4+16+9)=sqrt29$

Therefore,

$vecA.vecB-||vecA||*||vecB||$

$=-15-sqrt66*sqrt29=-58.75$

If A= <8 ,1 ,-1 >A= <8 ,1 ,-1 > and B= <-2 ,4 ,3 >B= <-2 ,4 ,3 >, what is A*B -||A|| ||B||A*B -||A|| ||B||?