$\begin{array}{l}a) \, \sqrt[-0,8]{(-0,125)^2}\\ = (-0,5^3)^{2.\tfrac{1}{-0,8}}\\ = (-0,5)^{-\tfrac{15}{2}}\\ \approx 181\\ b)\, \sqrt{(-2)^6}\\ = |-2|^3 = 8\\ c)\,\sqrt{(\sqrt 3 - 2)^2}\\ = |\sqrt3 - 2|\\ = 2 - \sqrt3\\ d) \, \sqrt{(2\sqrt2 - 3)^2}\\ = |2\sqrt2 - 3|\\ 3 - 2\sqrt2\end{array}$