Question

Jika X dan Y penyelesaian dari sistem persamaan 5x-2y = 25 dan 2x+3y = -9, nilai 2x+4y adlh ...

Answer 1

5x-2y=25
2x+3y=-9
2x+4y=...
 
caranya:
10x+15y=-45
10x-4y=50
_________ -
19y=-95
y=-95:19
y=-5

2x+3(-5)=-9
2x-15=-9
2x=-9+15
2x=6
x=6:2
x=3

2x+4y=?
2(3)+4(-5)=...
6-20=-14

Answer 2

5x-2y = 25  | x3 | 15x-6y = 75
2x+3y = -9  | x2 | 4x +6y = -18 +
                          19x      = 57
                            x        = 3

2x+3y = -9
6 + 3y = -9
    3y   = -15
     y    = -5

Jadi :
=> 2x+4y
=> 2.3+4.-5
=> 6-20
=> -14