akar-akar persamaan kuadrat x2 + (a-1)x + 2 = 0 adalah b dan c. Jika b = 2c dan a > 0, maka nilai a adalah…

Nilai a > 0 yaitu 4.
ingat rumus yg a + b = -b/a. dan a.b = c/a.
klu b = 2c , maka; b.c = c/a = 2/1 = 2
b + c = -b/a. = -(a-1)/1 = -a + 1.
trus buat kedlm persamaan…
b.c = 2
2c.c = 2
2c^2 = 2
maka, c = plus minus 1

b+c = -a + 1
2c + c = -a + 1
3c = -a + 1 (masukkan nilai c = -1)
3(-1) = -a + 1
-4 = -a
a = 4