Question

dados os vetores u=2,2, 1 , v= 1,3,0 , w=1,1,5 , marque a alternativa correta:

a ) u. (v x w ) = 25
b) u. (v x w ) = 44
c) u x v x w = 35
d) u.v.w = 45


ALGUÉM ME AJUDA?

Answer 1

Oi Mariane

seja u = (2,2,1), v = (1,3,0),  w = (1,1,5) 

(v x w)

i    j    k   i    j
1  3   0   1   3
1  1   5   1   5

det = 15i + 0j + 5k - 3k - 0i - 5j = 15i - 5j + 2k 

(v x w ) = (15, -5, 2)

u.(v x w) = (2,2,1)*(15, -5, 2) = 30 - 10 + 2 = 22 

u.v = 2 + 6 + 0 = 8

u.v.w = 8*(1,1,5) = 8 + 8 + 40 = 56 

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