Jika garis x+2y+3=0 tegak lurus pasa garis ax+3y+2=0 , maka a=

2y:-3-x
y : -3-x/2
jadi m : -1/2 agar tgk lurus m1m2:-1
jadi m2 : 2
3y:-ax-2
y : -ax-2/3
karena a : m
maka
2 : a/3
a : 6

garis saling tegak lurus
m1.m2 = - 1

x + 2y + 3 = 0 -->m1 = -1/2
ax  +3y + 2 = 0 -->m2 = - a/3

m1 . m2 = - 1
(-1/2) .(-a/3)= - 1
a/6= - 1
a = - 6