If $A= <6 ,-4 ,-1 >$ and $B= <2 ,-9 ,3 >$ , what is $A*B -||A|| ||B||$ ?

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Answer 1 · 2016-05-24T06:11:14

With the given data we start,

$A*B=<6*2,(-4)*(-9),(-1)*3>$

$A*B=<+12,+36,-3>$

$A*B=45$

$||A||=sqrt(6^2+(-4)^2+(-1)^2)$

$||A||=sqrt(36+16+1)$

$||A||=sqrt(53)$

$||A|| ~~7.28$

$||B||=sqrt(2^2+(-9)^2+3^2$

$||B||=sqrt(94)$

$||B|| ~~9.70$

Now lets plug in values

$A*B -||A|| ||B||=45-(7.28)(9.70)$

$A*B -||A|| ||B||=45-70.616$

$A*B -||A|| ||B||=-25.616$

If A= <6 ,-4 ,-1 >A= <6 ,-4 ,-1 > and B= <2 ,-9 ,3 >B= <2 ,-9 ,3 >, what is A*B -||A|| ||B||A*B -||A|| ||B||?