diketahui vektor-vektor a = (2,2,z) b = (-8,y,-5) c (x,4,y) dan d = (2x,22 - z,8).jika vektor a tegak lurus dengan vektor b dan vektor c sejajar dengan d maka (

a T b :
=> a•b = 0
=> [2 2 z]×[-8 y -5] = 0
=> -16+2y-5z = 0
=> 2y-5z = 16 ...(1)

c // d :
=> k.c = d
=> 2[x 4y 4] = [2x 22-z 8]
=> [2x 8y 8] = [2x 22-z 8]
Maka,
8y = 22-z
8y+z = 22 ...(2)
..

2y-5z = 16 —kali 4
8y+z = 22
-------------- --
-21z = 42
z = -2
..
2y-5(-2) = 16
2y = 6
y = 3

Sehingga, y+z = 3+(-2) = 1