Question

Titik A(3,y) terletakpada garis yang melalui titik K(-2,10)dan L(1,1] nilai y adalah

Answer 1

Cari persamaan garisnya dlu:
(y - y₁)/(y₂ - y₁) = (x - x₁)/(x₂ - x₁)
(y - 10)/(1 - 10) = (x + 2)/(1 + 2)
(y - 10)/-9 = (x + 2)/3
3y - 30 = - 9x - 18
9x + 3y - 12 = 0
substitusi (3,y) maka:
9(3) + 3y - 12 = 0
15 + 3y = 0
y = - 5

Answer 2

Gradien:
m=(y2-y1)/(x2-x1)
   = (1-10)/(1+2)
   = -3
-3=(10-y)/(-2-3)
15=10-y
y=-5