\[\sqrt{\left( - x^{2} + 2x - 2 \right)^{2}} =\]
\[= \sqrt{\left( x^{2} - 2x + 2 \right)^{2}} =\]
\[= \left| x^{2} - 2x + 2 \right| =\]
\[= x² - 2x + 2.\]