1. Pada sistem persamaan 4x - 5y = 13 dan 5x + 3y = 7 tentukan niĺai 3x + 4y

4x - 5y = 13 |×3
5x + 3y = 7 |×5
maka
12x - 15y = 39
25x + 15y = 35
----------------------(+)
37x = 74
x = 2
subtitusi
4x - 5y = 13
4(2) - 5y = 13
8 - 5y = 13
- 5y = 13 - 8
- 5y = 5
y = - 1
nilai 3x + 4y
= 3(2) + 4(-1)
= 6 - 4
= 2