hasil eliminasi: 7x = 7
7x = 7
x = 7/7
x = 1
subtitusi x = 1 ke pers 1
5x + 2y = 15
5(1) + 2y = 15
5 + 2y = 15
2y = 15 - 5
2y = 10
y = 10/2
y = 5
Jadi nilai (x,y) = (1,5)
jawaban: A
7. Selesaian dari 1/y + 2/x = 4 dan 3/y - 1/x = 5 adalah ....
cara:
1/y + 2/x = 4 ... pers 1
3/y - 1/x = 5 ... pers 2
eliminasi y dari pers 1 dan 2
1/y + 2/x = 4 (kali 3) -> 3/y + 6/x = 12
3/y - 1/x = 5 (kali 1) -> 3/y - 1/x = 5
hasil eliminasi: 7/x = 7
7/x = 7
7/7 = x
1 = x
subtitusi x = 1 ke pers 1
1/y + 2/x = 4
1/y + 2/1 = 4
1/y = 4 - 2
1/y = 2
1/2 = y