Diketahui 3x + 4y = 7 dan -2x + 3y = -16. Nilai 2x - 7y adalah ?

Materi : Program Linear
Bahasan : Persamaan Linear 2 Variabel
Metode : Eliminasi - Substitusi
Jawaban : 24

Langkah - langkah :
 3x + 4y = 7       (x2)
-2x + 3y = - 16   (x3)
6x + 8y = 14
- 6x + 9y = - 48
---------------------- +
17y = - 34
y = - 2
Substitusi
6x + 8(- 2) = 14
6x - 16 = 14
6x = 30
x = 5
Nilai 2x - 7y
2(5) - 7(-2)
10 + 14 = 24

Persamaan Linear Dua Variabel
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3x + 4y = 7 ...... × (2) ..... 1)
-2x + 3y = -16 ... × (-3) .....2)
••••••••••••••••••••••••••••
6x + 8y = 14
6x - 9y = 48
•••••••••••••••••••••••••••• (-)
8y - (-9y) = 14 - 48
8y + 9y = - 34
17y = -34
y = -2

Subs. Nilai Y ke pers. 1 ataupun 2 !

3x + 4y = 7
3x + 4(-2) = 7
3x + (-8) = 7
3x = 7 + 8
3x = 15
x = 5

Hp = { 5, -2}

2x - 7y => 2(5) - 7(-2)
2x - 7y => 10 + 14 => 24


Semoga Membantu
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