nomor 8 pakai caranya...

6x² + x - 2 = 0
a = 6
b = 1
c = -2

x1 + x2 = -b/a
x1 + x2 = -1/6
x1 = -1/6 - x2

x1 . x2 = c/a
(-1/6 - x2) . x2 = -2/6
-1/6x2 - x2² = -1/3 (kali 6 kedua ruas)
-x2 - 6x2² = -2
0 = 6x2² + x2 - 2
0 = 6x2² - 3x2 + 4x2 - 2
0 = 3x2(2x2 - 1) + 2(2x2 - 1)
0 = (2x2 - 1)(3x2 + 2)

2x2 - 1 = 0
2x2 = 1
x2 = 1/2
atau
3x2 + 2 = 0
3x2 = -2
x2 = -2/3

Jika x2 = 1/2, maka:
x1 = -1/6 - x2
x1 = -1/6 - 1/2
x1 = -1/6 - 3/6
x1 = -4/6 = -2/3

Jika x2 = -2/3, maka:
x1 = -1/6 - x2
x1 = -1/6 - (-2/3)
x1 = -1/6 + 2/3
x1 = -1/6 + 4/6
x1 = 3/6 = 1/2

Karena x1 > x2, maka nilai x1 = 1/2 dan x2 = -2/3
x1 - x2 = 1/2 - (-2/3)
x1 - x2 = 1/2 + 2/3
x1 - x2 = 3/6 + 4/6
x1 - x2 = 7/6 = 1 1/6

Jawaban: C