gimana nih masih bingung tolong penjelasannya dong

Mapel : Matematika
Bab : Persamaan garis lurus

16)

Jawaban : A
tegak lurus : m1 × m2 = -1

y = 2x + 5
y = 2/1x + 5/1
0 = 2x + 5

m1 = 2

x + 2y + 3 = 0
2y = -x - 3
y = -1/2x -3/2
0 = -1/2x - 3/2

m2 = -1/2

m1 × m2 = -1
2 × (-1/2) = -1
-1 = -1

=> Terbukti <=

17)

(-4,3) dan m = 2

y - y1 = m(x - x1)
y - 3 = 2(x - (-4))
y - 3 = 2x + 8
0 = 2x - y + 8 + 3
0 = 2x - y + 11

(A)