Diketahui garis g1 : 2x-y-3=0, g2 : y=-2x+2, g3 : x+2y-1=0 dan g4 melalui titik potong g1 dan g2 serta tegak lurus g3. Persamaan garis lurus g4 adalah Harap ser

g1 : 2x - y - 3 = 0 => 2x - y = 3
g2 : y = -2x + 2 => 2x + y = 2
Titik potong g1 dan g2
2x - y = 3
2x + y = 2
-------------- +
4x = 5 => x = 5/4
2x + y = 2 => y = 2 - 2x = 2 - 2(5/4) = 2 - 5/2 = -1/2
Jadi titik potong (5/4, -1/2)

g3 : x + 2y - 1 = 0 => m = -a/b = -1/2 karena tegak lurus (m1 . m2 = -1)
Maka : -1/2 . m = -1 => m = -1/(-1/2) = 2

Persamaan garis g4 melalu (5/4, -1/2) dan m = 2
y - y1 = m(x - x1)
y - (-1/2) = 2(x - 5/4)
y + 1/2 = 2x - 5/2
y = 2x - 5/2 - 1/2
y = 2x - 3

2x - y - 3 = 0