1. Tentukan persamaan garis lurus yang melalui titik (1,-3) dan sejajar dengan garis 2x + 4y = 8 2. Tentukan persamaan garis lurus yang melalui tituk (3,5) dan

1. y-y1 = m(x-x1)
y+3 = -1/2(x-1)
___________ x 2
2(y+3) = -1(x-1)
2y+6 = -x+1
2y+x = 1-6
2y+x = -5

2. y-y1 = m(x-x1)
y-5 = -1/3(x-3)
__________ x 3
3y-15 = -x+3
3y+x = 3+15
3y+x = 18

Bab Persamaan Garis
Matematika SMP Kelas VIII

1] ax + by = c, sejajar, (p, q)
    ax + by = ap + bq

   2x + 4y = 8, sejajar, (1, -3)
   2x + 4y = 2 . 1 + 4 .(-3)
   2x + 4y = 2 - 12
   2x + 4y = -10
   x + 2y = -5

2] ax + by = c, tegak lurus, (p, q)
    bx - ay = bp - aq

    3x - y = 2, tegak lurus, (3, 5)
    -x - 3y = (-1) . 3 - 3 . 5
    -x -3y = -3 - 15
    -x - 3y = -18
     x + 3y = 18