2x + 3y - 4 = 0 tegak lurus dengan 2mx + (m+3)y + m = 0, maka nilai m adalah

2x + 3y - 4 =0
3y = - 2x + 4
y = - 2/3x + 4/3 ...... m1 = - 2/3

2mx + (m+3)y + m = 0
(m+3)y = - 2mx - m
y = -2m/(m+3)x - m/m+3 .... m2 = - 2m/m+3

m1 × m2 = - 1
- 2/3 × (-2m/m+3) = - 1
-2/3 × (-2m) = - 1 (m+3)
4m/3 = - m - 3
4m = 3 (-m - 3)
4m = - 3m - 9
4m + 3m = - 9
7m = - 9
m = - 9/7

Jadi nilai m = - 9/7