Akar akar persamaan y^2 – py + 18 = 0 adalah m dan n. Jika nilai m = 2n, tentukan nilai p !

Bab Persamaan Kuadrat
Matematika SMP Kelas VIII

y^2 – py + 18 = 0
a = 1; b = – p; c = 18

m = 2n

m x n = c/a
2n x n = 18/1
2n^2 = 18
n^2 = 18/2
n = akar 9
n = 3

m = 2n
m = 2 x 3
m = 6

m + n = -b/a
6 + 3 = -(-p)/1
p = 9

atau
n = – 3

m = 2n
m = 2 x (-3)
m = -6

m + n = -b/a
– 6 + (-3) = – (-p)/1
p = – 9

jadi, p = 9 atau p = – 9