Tolong pakai caranya dong Di ketahui vektor u = 3 2 1 dan v= 2 3 -1 jika b = 2u - 3v dan a = u + 2v maka nilai a.b = ..... A 45 B 38 C 35 D - 35 E - 45

Dik : Vektor U = ( 3,2,1 )
V = ( 2,3-1 )
jika - 2u -3v = b
- u+2v = a
Dit: nilai a.b?
jawab:
1. mencari "b" = 2u-3v
= 2(3,2,1) - 3(2,3,-1)
= (6,4,2) - (6,9,-3)
= (0,-5,5).
2. mencari "a" = u + 2v
= (3,2,1) + 2(2,3,-1)
= (3,2,1) + (4,6,-2)
= (7,8,-1)
3. menacari "a.b" = (0,-5,5) . (7,8,-1)
= (0,-40,-5)
》0-40-5
》 -45
jadi jawabannya E. -45