Nilai X yg memenuhi 4x+4y=5 dan y=x-5 adalah

Cara Subtitusi:
• 4x + 4y = 5 .... pers 1
• y = x - 5 .... pers 2
Subtitusi pers 2 ke pers 1
4x + 4y = 5
4x + 4(x-5) = 5
4x + 4x - 20 = 5
8x = 5 + 20
8x = 25
x = 3,125

Cara Eliminasi
• 4x + 4y = 5 ...pers 1
• y = x - 5
=> x - y = 5 ...pers 2
Eliminasi pers 1 dan 2 (Eliminasi y)
4x + 4y = 5 | x1 |
x - y = 5 | x4 |
_____________
4x + 4y = 5
4x - 4y = 20
__________+
8x = 25
x = 25/8
x = 3,125

4x+4y = 5
4x = 5 - 4y
x = 5 - 4y / 4

Maka
x = 5 - 4 (x - 5) / 4
4x = 5 - 4x + 20
8x = 25
x = 3,125