Diketahui x1 dan x2 adalah akar-akar persamaan kuadrat x² + 4x + ( a-4 ) = 0. Jika x1 = 3x2, maka nilai a yang memenuhi adalah?. Tolong jawabannya

x1 + x2 = -4
3x2 + x2 = -4
4x2 = -4
x2 = -1

x1 . x2 = (a - 4) / 1
3x2 . x2 = a - 4
3(-1) . (-1) = a - 4
3 = a - 4
a = 7

Persamaan Kuadrat

x² + 4x + (a - 4) = 0
a = 1
b = 4
c = a - 4

x1 = 3 . x2

x1 + x2 = -b/a = -4
3 x2 + x2 = -4
4 x2 = -4
x2 = -1

x1 × x2 = c/a = a - 4
3x2 . x2 = a - 4
3 x² = a - 4
3(-1)² = a - 4
a = 3 + 4
a = 7 ✔