Garis x+2y-7=0 dicerminkan terhadap garis y=-x

Pencerminan

x + 2y - 7 = 0
thd y = -x

(x,y)
x' = -y
y' = -x

x + 2y - 7 = 0
-y' + 2(-x') - 7 = 0
-y' - 2x' - 7 = 0
-y - 2x - 7 = 0 ✔

Hasil pencerminan :
-y - 2x - 7 = 0