Question

Penyelesaian sistem persamaan linear :
2x + 3y = 20 dan 3x + 5y = 15 adalah x dan y.
Nilai dari x + 2y =...

Answer 1

Verified answer

Mapel : Matematika
Bab : Sistem Persamaan Linear Dua Variabel (SPLDV)

2x + 3y = 20    (kali 3)
3x + 5y = 15    (kali 2)

6x + 9y = 60
6x + 10y = 30
------------------- -
           -y = 30
            y = -30

      2x + 3y = 20
2x + 3(-30) = 20
  2x + (-90) = 20
             2x = 20 + 90
             2x = 110
               x = 110/2
               x = 55

x + 2y
= 55 + 2(-30)
= 55 + (-60)
= -5

Answer 2

Verified answer

2x + 3y = 20    dikalikan 3 menjadi      6x +   9y = 60
3x + 5y = 15    dikalikan 2 menjadi      6x + 10y = 30
                                                          ---------------------- -
                                                                     - y  = 30   →  y = -30
2x + 3y        = 20
2x + 3 (-30) = 20
2x - 90        = 20
             2x  = 20 + 90
             2x  = 110
               x  = 55

nilai  x + 2y = 55 + 2 (-30)
                   = 55 - 60
                   = - 5