Tolong guys nomer 6 beserta cara, tapi caranya horner makasih heheheehe

f(x) = 6x^3 + ax^2 - 3x + b

1) f(x) habis dibagi (2x - 1) berarti sisanya 0
1/2 | 6 .... a ........ -3 ................ b
..... | ........ 3 ....... (a + 3)/2 ..... (a - 3)/4
-------------------------------------------------- +
....... 6 ... a + 3 ... (a - 3)/2 ..|.. b + (a - 3)/4 => sisa
b + (a - 3)/4 = 0
(a - 3)/4 = -b
a - 3 = -4b
a = 3 - 4b

2) f(x) : (x - 2) bersisa 39
2 | 6 ... a ........... -3 .............. b
.. | ....... 12 ......... 2a + 24 ... 4a + 42
----------------------------------------------- +
... 6 ... a + 12 ... 2a + 21 ..|.. b + 4a + 42 => sisa
b + 4a + 42 = 39
b + 4(3 - 4b) = 39 - 42
b + 12 - 16b = -3
-15b = -15
b = 1

a = 3 - 4b = 3 - 4(1) = -1

Jadi a = -1 dan b = 1