Question

Tentukan persamaan garis lurus yang melalui titik potong garis 4x + 7y - 15 = 0 dengan garis 9x - 14y - 4 = 0. dan tegak lurus pada garis 21x + 5y - 3 = 0

Answer 1

4X + 7Y = 15
9X - 14Y = 4

8X + 14Y = 30
9X - 14Y = 4

17X = 34
X = 2
Y = 1
m = 5/21
Y - 1 = 5/21 (X - 2)
21Y - 21 = 5X - 10
5X - 21Y + 11 = 0

Answer 2

4x + 7y - 15 = 0  ...(1)
9x - 14y - 4 = 0   ...(2)
21x + 5y - 3 = 0  ...(3)

4x + 7y = 15  ...(1)
9x - 14y = 4   ...(2)
21x + 5y = 3  ...(3)

(1) x 2  8x + 14y = 30  ...(1)'
(2) + (1)'  17x = 34
                  x = 2 ...(4)

Substitusikan ke x = 2 ke (1),
8 + 7y = 15
7y = 7 (15 - 8)
y = 1

x = 2
y = 1