19. Jika titik A (4,2,q), B(2,-2,1), dan C(8,p+2,-8) segaris, nilai p+q=.... a. 10 d. -6 b. 8 e. -10 c. 6 beserta caranya!

Jika titik A (4,2,q), B(2,-2,1), dan C(8,p+2,-8) segaris

Segaris maka
AB = k AC

k = koefisien

AB = b - a = (2, -2, 1) - (4, 2, q) = (-2, -4, 1 - q)
AC = c - a = (8, p + 2, -8) - (4, 2, q) = (4, p, -8 - q)

AB = k AC
(-2, -4, 1 - q) = k (4, p, -8 - q)

-2 = 4k
k = -½

-4 = kp
-4 = (-½) p
p = -2 × -4 = 8

1 - q = k (-8 - q)
1 - q = -½ (-8 - q)
-2 (1 - q) = - 8 - q
-2 + 2q = -8 - q
2q + q = -8 + 2
3q = -6
q = -2

p + q = 8 + (-2) = 6