Question

Penyelesaian dari sistem persamaan 2x-5y=-16 dan 5x+2y=-11adalah x dan y.nilai 7x-8y adalah

Answer 1

10x-25y=-80
10x+4y=-22 -
    -29y= -58
         y = 2
5x+2.2=-11
      5x = -15
        x = -3
7x-8y = 7.(-3) - 8.2 = -21-16= -37

Answer 2

2x - 5y = -16 -> kali 5 -> 10x -25y = -80
5x + 2y = -11 -> kali 2 -> 10x + 4y = -22
hasil pengurangan : -29y = -58
jadi, y = -58/-29 = 2

2x - 5y = -16
2.x - 5.2 = -16
2x - 10 = -16
2x = - 16 + 10
2x = -6
x = - 3

HP = {x, y} = {-3,2}

7x - 8y =
= 7.-3 - 8.2
= -21 - 16
= -37