penyelesaian sistem pers x+2y=-5 dan 3x-4y=25 adalah x=r dan y=s, tentukan nilai 2r. 1/4s

MAPEL = MATEMATIKA
KELAS = 8
BAB = SPLDV

eliminasi nilai y
x + 2y = -5 |×2
3x - 4y = 25 |×1

2x + 4y = -10
3x - 4y = 25
___________+
5x = 15
x = 15/5
x = 3

subtitusi nilai x
x + 2y = -5
3 + 2y = -5
2y = -5 - 3
2y = -8
y = -8/2
y = -4

x = r = 3
y = s = -4

nilai 2r . ¼s :
= 2(3) . ¼(-4)
= 6 . -1
= -6

semoga membantu