If #A= <-3 ,8 ,-1 ># and #B= <0 ,7 ,2 >#, what is #A*B -||A|| ||B||#?

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Answer 1 · 2017-02-08T07:24:46

The answer is #=-8.63#

The dot product is

#vecA.vecB=<-3,8,-1>.<0,7,2>=0+56-2=54#

The modulus of #vecA# is

#||vecA||=||<-3,8,-1>=sqrt(9+64+1)=sqrt74#

The modulus of #vecB# is

#||vecB||=||<0,7,2>=sqrt(0+49+4)=sqrt53#

Therefore,

#vecA.vecB-||vecA||*||vecB||#

#=54-sqrt74*sqrt53#

#=54-62.63#

#=-8.63#