If A=<6,9,−1> and B=<−4,−9,4>, what is A⋅B−||A||||B||?

1 Answer
ali ergin
Mar 12, 2016

A⋅B−||A||||B||=−224,47

Explanation:

A=<6,9,−1> B=<−4,−9,4>
A=<a,b,c> B=<d,e,f>
A⋅B=a⋅d+b⋅e+c⋅f
A⋅B=−24−81−4=−109
||A||=√a2+b2+c2 ||A||=√36+81+1=√118
||B||=√d2+e2+f2 ||B||=√16+81+16=√113
A⋅B−||A||||B||=−109−(√118⋅√113)
A⋅B−||A||||B||=−109−√118⋅113
A⋅B−||A||||B||=−109−115,47
A⋅B−||A||||B||=−224,47

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