persamaan kuadrat x^2 - ax + a + 1 = 0 mempunyai akar akar x1 dan x2. Jika x1-x2 = 1, maka a = ...

x^2 - ax + a + 1 = 0

p = 1
q = -a
r = a + 1

x1 + x2 = -q/p = -(-a)/1 = a
x1.x2 = r/p = (a + 1)/1 = a + 1

x1 + x2 = a
x1 - x2 = 1
__________ +
2x1 = a + 1

x1.x2 = a + 1
x1.x2 = 2x1
x2 = 2

x1 - x2 = 1
x1 - 2 = 1
x1 = 3

x1 + x2 = a
3 + 2 = a
a = 5