tolong jwb pakai cara ya :) 21.persamaan garis yg sejajar dgn garis 4x-2y+9=0 adalah 1.4y-2x=4 2.y-2x=-2 3.6x-2y=8 4.3y-6x-6=0 A.1 dan 2. B.2 dan 3 c.1 dan

cuman bisa bantu no. 25
5x+y =7
3x-y =9
_______+
8x =16
x =16: 8
x=2
jadi jawaban no. 25 : c. 2

21) 4x - 2y + 9 = 0
- 2y = - 4x - 9
m = - 4/-2
m = 2
gradien sejajar m1 = m2 = 2
1) 4y - 2x = 4
4y = 2x + 4
m = 2/4 = ½ ( salah )
2) y - 2x = - 2
y = 2x - 2
m = 2/1 = 2 ( benar )
3) 6x - 2y = 8
- 2y = - 6x + 8
m = -6/-2 = 3 ( salah )
4) 3y - 6x - 6 = 0
3y = 6x + 6
m = 6/3 = 2 ( benar )
jadi jawabnya 2 dan 4 ( D )


25) 5x + y = 7
3x - y = 9
--------------------(+)
8x = 16
x = 2 ( C )

28) misal
bil 1 = x
bil 2 = y
x + y = 41
x - y = 15
--------------(+)
2x = 56
x = 28
subtitusi
x - y = 15
28 - y = 15
- y = 15 - 28
- y = - 13
y = 13
nilai x • y
= 28 • 13
= 364 ( C )

29) misal
mobil = x
motor = y
x + y = 40 |×2
4x + 2y = 110
maka
2x + 2y = 80
4x + 2y = 110
--------------------(-)
- 2x = - 30
x = 15
subtitusi
x + y = 40
15 + y = 40
y = 40 - 15
y = 25
uang parkir
= 15x + 25y
= 15(2.000) + 25(5.000)
= 30.000 + 125.000
= 155.000 ( tdk ad opsi pilihan)