Tolong bantu jawab, makasih

a = (4 , -12 , -6)
b = (4 , 2 , -4)

a.b = 4×4 + (-12)×2 + (-6)×(-4)
= 16 - 24 + 24
= 16
|b| = akar [4^2 + 2^2 + (-4)^2]
= akar [16 + 4 + 16]
= akar 36
= 6
|b|^2 = 6^2
= 36
Proyeksi orthogonal vektor a terhadap vektor b

a . b
_____ × b
|b|^2

= 16
_____ × (4 , 2 , -4)
36

= 4
______× (4 , 2 , -4)
9

= [(4×4)/9 , (4×2)/9 , (4×(-4))/9]
= (16/9 , 8/9 , -16/9)
c = (16/9 , 8/9 , -16/9)
panjang vektor c
= akar [(16/9)^2 + (8/9)^2 + (-16/9)^2]
= akar [256/81 + 64/81 + 256/81]
= akar [576/81]
= akar 64/9
= 8/3

Panjang vektor d
= akar [2^2 + 1^2 + x^2]
= akar [4 + 1 + x^2]
= akar [5 + x^2]

Panjang vektor c = panjang vektor d

8/3 = akar [5 + x^2]
5 + x^2 = [8/3]^2
5 + x^2 = 64/9
x^2 = 64/9 - 5
x^2 = 64/9 - 45/9
x^2 = 19/9
x = akar 19/9