Question

Soal UM-UGM 2005 tentang Persamaan Kuadrat.No.9
Ada yang bisa ngerjain ini gaa ?

Answer 1

Verified answer

UM - UGM 2005

x² + 2bx + 32 = 0
Akar2 nya positif ---> β > α

Deret Geometri
α, β, 4α

r = β/α = 4α/β
β² = 4α²
β = 2α

α × β = c/a = 32
α × 2α = 32
2α² = 32
α = 4

β = 2α = 8

α + β = -b/a = -2b
4 + 8 = -2b
b = 12/-2
b = -6

Jadi, b = -6
(opsi A)