n^3+an-2=kn^2+bkn+2k
n^3-kn^2+(a-bk)n-2(1-k)=0
k=n+c
-c^n^2+an-bn^2-bcn-2+2n+2c=0
(-c-b)n^2+(a-bc+2)n+2c-2=0
c=1
b=-1
a=-3