jika (m, 3n) merupakan penyelesaian sistem persamaan kuadrat y=2ײ+5×+8 dan y=ײ-5×-17 .nilai 2m - n =

jawab

y₁ = 2x² + 5x + 8
y₂ = x² - 5x - 17

y₁ = y₂
2x² + 5x + 8  = x² - 5x - 17
x² + 10 x + 25 = 0
(x+5)² = 0
x = - 5
y= x² - 5x -17
y = (-5)² -5(-5) - 17
y = 25 + 25 -17
y = 33

x = m = -5
y = 3n = 33 → n = 11

nilai 2m - n = 2(-5)  - (-11)
2m - n = -10  + 11
2m - n = 1