sama caranya ya ka.... A. 10 B. 4 C. -4 D. -6 E. -5/8

x^2 + ax + b = 0
x1 + x2 = -a
x1 . x2 = b
x^2 + cx + a = 0
x3 + x4 = -c
x3 . x4 = a
x3 = 2x1 dan x4 = 2x2
x3 + x4 = 2x1 + 2x2
x3 + x4 = 2(x1 + x2) = 2(-a) = -2a
- c = -2a => c = 2a
x3 . x4 = 2x1.2x2 = 4x1.x2 = 4b
a = 4b => b = a/4
(a + b)/c = (a + a/4)/2a
= (4a + a)/4/(2a)
= (5a)/8a
= 5/8