Kerjakan nomor 9 pakai cara

Bab Program Linear
Matematika SMA Kelas XI

titik potong 
6x + 2y = 12 → dikali 3 → 18x + 6y = 36
2x + 6y = 12

18x + 6y = 36
  2x + 6y = 12
------------------- -
        16x = 24
           x = 24/16
           x = 3/2

2x + 6y = 12
2. 3/2 + 6y = 12
3 + 6y = 12
6y = 12 - 3
y = 9/6
y = 3/2

(3/2, 3/2)

f(x,y) = 4x + 5y

f(2, 0) = 4 . 2 + 5 . 0 = 8

f(0, 2) = 4 . 0 + 5 . 2 = 10

f(3/2, 3/2) = 4 . 3/2 + 5 . 3/2
                = 6 + 15/2
                = 6 + 7 1/2
                = 13 1/2

jawabannya E