Jawabanmu

2014-02-09T23:18:22+07:00
Alfa x betha = 2
alfa + betha = a-1
alfa = 2 betha
alfa = 2
betha = 1
2+1 = a-1
3= a-1
a= 4
2014-02-09T23:20:27+07:00
Diketahui : x^2 + (a-1) x + 2 = 0
α =2β
jawab
α.β = 2/1 = 2
2β.β = 2
β^2 = 1
β = 1 atau -1
untuk β = 1
α = 2
untuk β = - 1
α = -2
α +β = -(a-1)/1 = -a + 1
untuk β = 1
α = 2
α +β = -a + 1
1 + 2 = -a + 1
3 = -a +1
a = 1- 3 = -2 TM
untuk β = -1
α = -2
α +β = -a + 1
-2 -1 = -a + 1
-3 = -a + 1
-a = -4
a = 4 memenuhi
jadi nilai a = 4