Tentukan persamaan garis – garis berikut.

a) m = -⅔

titik (3, -8)

a)

Y-Y1 = M ( X – X1)

y -(-8) = -⅔ (x – 3)

y + 8 = -⅔ (x -3)

3( y+8) = -2(x -3)

3y + 24 = -2x + 6

2x + 3y +24 -6 = 0

2x + 3y + 18 = 0

b) garis h melalui titik (-7 , -3) dan (-1,5)

y – y1 = x – x1

_____ _____

y2 -y1 x2 – x1

y -(-3) = x – (-7)

____ _____

5 – (-3) -1 – (-7)

y + 3 = x + 7

____ ____

8 6

6(y+3) = 8(x+7)

6y +18 = 8x + 56

-8x + 6y +18 -56 = 0

-8x + 6y -38 = 0

c) garis l melalui titik (4,-5) dan tegak lurus garis 2x -6y = 9

Persamaan umum : 2x -6y -9 = 0

m = -a -2 2

___ = ___ = ___

b -6 6

Tegak lurus m (gradiennya lawan dan kebalikan)

m = – 6

__ = -3

2

y – y1 = m ( x – x1)

y -(-5) = -3 (x – 4)

y + 5 = -3x + 12

3x + y + 5 – 12 = 0

3x + y -7 = 0