Verified answer

(x+3)³=9(x+3)

x³+9x²+27x+27=9x+27

x³+9x²+27x+27-9x-27=0

x³+9x²+18x=0

x(x²+9x+18)=0

x=0

x²+9x+18=0

x²+9x+18=0

D=9²-4*18=81-72=9=3²

x₁= -6

x₂= -3

x₃=0