Question

Akar-akar persamaan xkuadrat -8x +p = 0 adalah x1 dan x2 . Untuk 3x1 + 5x2 = 20, maka nilai p

Answer 1

X²-8x + p = 0
a= 1, b = -8, c = p
x₁ + x₂ = -b/a = -(-8) / (1) = 8
x₁ . x₂ = c/a = p/1 = p

eliminasi 3x₁ + 5x₂ = 20  dengan  x₁ + x₂ = 8
3x₁ + 5x₂ = 20
3x₁ + 3x₂ = 24  .....(-)
..........2x₂ = -4
x₂ = -2
x₁ + x₂ = 8
x₁ -2 = 8
x₁ = 10

nilai p = x₁ x₂
p = (10) (-2)
p = - 20