Answer
{$-1-i,-1+i$}
Work Step by Step
Given: $x^2+2x+2=0$
This can be re-written as: $x^2+2x=-2$
We need to add $(1)^2$ to complete the square.
Thus,
$x^2+2x+1=-2+1$
or, $(x+1)^2=-1$
or, $(x+1)=\pm \sqrt {-1}$
or, $x=-1+i,-1-i$
Hence, solution set is $x=${$-1-i,-1+i$}