Question

Am I right!?

Answer 1

to check substitute in your solutions
\[f(2)=9(2)^3-21(2)^2+4(2)+4=0\]
\[f(-1/3)=9(-1/3)^3-21(-1/3)^2+4(-1/3)+4=0\]
\[f(2/3)=9(2/3)^3-21(2/3)^2+4(2/3)+4=0\]

they all solve the system \[\checkmark\checkmark\checkmark\]

Answer 2

thanks!

Answer 3

how did you get those solutions?