x³-kx²-x+3
=(x-1)(ax²+bx+c)
=ax³+(b-a)x²+(c-b)x-c
a=1
-c=3 c=-3
c-b=-1 b=c+1=-2
b-a=k=-2-1=-3
所以 k=-3
x³+-3x²-x+3
=(x-1)(x²-2x-3)
=(x-1)(x-3)(x+1)
x³-kx²-x+3
=(x-1)(ax²+bx+c)
=ax³+(b-a)x²+(c-b)x-c
a=1
-c=3 c=-3
c-b=-1 b=c+1=-2
b-a=k=-2-1=-3
所以 k=-3
x³+-3x²-x+3
=(x-1)(x²-2x-3)
=(x-1)(x-3)(x+1)