If #A= <2 ,6 ,-3 ># and #B= <3, -5, 3 >#, what is #A*B -||A|| ||B||#?

Question

1322 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2016-09-20T08:26:19

#- 33 - 7 sqrt(43)#

We have: #A = <2, 6, - 3># and #B = <3, - 5, 3>#

#=> A cdot B - abs(A) abs(B) = <2, 6, - 3> cdot <3, - 5, 3> - abs(<2, 6, - 3>) abs(<3, - 5, 3>)#

#=> A cdot B - abs(A) abs(B) = (2 cdot 3) + (6 cdot (- 5)) + ((- 3) cdot 3) - sqrt(2^(2) + 6^(2) + (- 3)^(2)) cdot sqrt(3^(2) + 5^(2) + 3^(2))#

#=> A cdot B - abs(A) abs(B) = 6 - 30 - 9 - sqrt(4 + 36 + 9) cdot sqrt(9 + 25 + 9)#

#=> A cdot B - abs(A) abs(B) = - 33 - sqrt(49) cdot sqrt(43)#

#=> A cdot B - abs(A) abs(B) = - 33 - 7 sqrt(43)#