Determine all the [roots](https://artofproblemsolving.com/wiki/index.php/Root), [real](https://artofproblemsolving.com/wiki/index.php/Real) or [complex](https://artofproblemsolving.com/wiki/index.php/Complex), of the system of simultaneous [equations](https://artofproblemsolving.com/wiki/index.php/Equation)

$x+y+z=3$,
$x^2+y^2+z^2=3$,

$x^3+y^3+z^3=3$.
Let $x$, $y$, and $z$ be the [roots](https://artofproblemsolving.com/wiki/index.php/Root) of the [cubic polynomial](https://artofproblemsolving.com/wiki/index.php/Cubic_polynomial) $t^3+at^2+bt+c$. Let $S_1=x+y+z=3$, $S_2=x^2+y^2+z^2=3$, and $S_3=x^3+y^3+z^3=3$. From this, $S_1+a=0$, $S_2+aS_1+2b=0$, and $S_3+aS_2+bS_1+3c=0$. Solving each of these, $a=-3$, $b=3$, and $c=-1$. Thus $x$, $y$, and $z$ are the roots of the polynomial $t^3-3t^2+3t-1=(t-1)^3$. Thus $x=y=z=1$, and there are no other solutions.