diketahui f(x)=x³-4x²+ax+b habis dibagi (x²-3x+2) nilai a-b=

f (x) = x^3 -4x^2 + ax + b.
pembagi (x^2 -3x +2) => (x -1)(x -2)
x = 1 dan x = 2
f (1) = 1^3 -4(1)^2 + a.1 + b = 0
1 - 4 + a + b = 0
a + b = 3....(1)
f (2) = 2^2 -4(2) + a.2 + b = 0
4 -8 + 2a + b = 0
2a + b = 4....(2)
a + b = 3.......(1)
--------------------- -
a = 1
a + b = 3
1 + b = 3
b = 2
a - b = 1 - 2 = -1