Theo đề bài ta có: `z=1+i=>` $\left \{ {{z^2=2i} \atop {z^3=-2+2i}} \right.$
`⇒` $\left \{ {{(-2+2i)+a(2i+6(1+i)+c=0} \atop {8+4a+bz+c=0}} \right.$
`=>` $\left \{ {{2+b+c+(2a+b+2)i=0} \atop {4a+2b+c=-8}} \right.$
`=>` \begin{cases} b+c-2=0 \\ 2a+b+2=0 \\ 4a+2b+c=-8 \end{cases}
`=>` \begin{cases} a=-4 \\ b=6\\ c=-4 \end{cases}
`=> a+b+c=-2`
`=>` Chọn `A`
