a. Tentukan garis-garis yang sejajar.
b. Tentukan garis-garis yang saling tegak lurus.
4.Diketahui beberapa garis dengan persamaan berikut : Garis k: 2x+3y-5 =0 Garis : y = ²x +7 Garis m y=-x +6 Garis n 3x-2y +9 =0
JAWABAN :
1) 4x – 2y + 5 = 0 – 1/2y = – 4x – 5 gradien saling tegak lurus
m = – 4-1/2
m = 8
m1. m2 = – 1 8. m2 = 1
m2 = 1/8
2) (y – y1)/(y2 – y1) = (x-x1)/(x2-x1)
(y-2)/(-1-2) = (x + 3) / ( 5 + 3) (y-2)/-3 = (x + 3) / 8
8 (y-2)=-3 (x + 3)
8y- 16 = 3x – 9 8y + 3x = -9 + 16
8y + 3x = 7
3) y = 3/2 x + 9 m = 3/2
gradien saling tegak lurus
m1. m2 = 1 3/2 m2 = – 1
m2 = 2/3
pera garis
y – y1= m ( x – x1)
y + 3 = -2/3 (x + 2)
y=-2/3 x – 4/3 – 3 ( dikalikan 3)
(4. ) (y – y1)/(y2 – y1) = (x-x1)/(x2-x1) (y-O)/(3-0) = (x – 0) / (2-0)
y/3 =x/2
2y = 3x
2y – 3x = 0
3y = 7 – 6x
m = -6/3
m = -2
gradien saling tegak lurus
m1. m2 = -1
– 2. m2 = -1
m2 = 12
pers garis
y – y1= m ( x-x1)
y + 2 = 1/2 (x-4) y = 12x-2-2
y = 1/2 x – 4 (dikali 2)
2y = x – 8
2y-x+8 = 0
persamaan yg gradienya 3:
c) 6x – 2y = 12
– 2y = – 6x + 12
m = -6/-2
m = 3
5) 3x – 6y + 5 = 0
– 6y=-3x – 5
m = -3/-6
3y – 2x – 49 3y + 2x = – 13
6) 4x – 2y = 6
– 2y = – 4x + 6
m = -4/-2
m = 2
7) 3x – 2y = 6 – 2y = – 3x + 6 m = 3/2
m = -3/-2
gradien saling sejajar m1 = m2 = 3/2
pers garis
y – y1= m ( x-x1) y = 3/2 x – 9-6 y = 3/2 x 15 ( dikali 2)
y + 6 = 3/2 (x – 6)
2y = 3x – 30
2y – 3x + 30 = 0
8) 3x – 5y = 10
– 5y = – 3x + 10
m = -3/-5
m = 3/5
9) y – y1= m ( x – x1) y-x+8 = 0
y + 5 = 1(x-3) y=x-3-5
y = x – 8
10) x – 2y + 4 = 0
– 2y = -x – 4
11) 3x + 7y – 9 = 0
7y=-3x + 9
m = -3/7 gradien saling tegak lurus
m1. m2 = 1
– 3/7. m2 = -1
m2 = 7/3
pers garis y – y1= m ( x – x1)
y + 1 = 7/3 (x-6)
y = 7/3x – 14 – 1
y = 7/3 x 15 (dikali 3)
3y = 7x – 45 3y – 7x + 45 = 0
12) m = (y2 – y1)/(x2-x1) m = (-8+3)/(3-5)
m = -5/-2
m = 5/2
13) y = 2/3x + 9
pers garis
y – y1= m ( x – x1)
m = 23 3y = 2x + 2-9
y + 3 = 2 ( x + 1) y = 23 x + 2/3-3 (dikali 3)
3y – 2x = -7
(14) y = – 3x + 2
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