I,
a,
\(\left|x\right|=\left|-2,5\right|\\ \Rightarrow\left|x\right|=2,5\\ \Leftrightarrow\left\{{}\begin{matrix}x=2,5\\x=-2,5\end{matrix}\right.\\ Vậyx\in\left\{-2,5;2,5\right\}\)
b,
\(\left|x-2\right|=\dfrac{4}{5}\\ \Rightarrow\left\{{}\begin{matrix}x-2=\dfrac{4}{5}\\x-2=-\dfrac{4}{5}\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{14}{5}\\x=\dfrac{6}{5}\end{matrix}\right.\\ Vậyx\in\left\{\dfrac{14}{5};\dfrac{6}{5}\right\}\)
II,
\(a,-5,17-0,469=-5,639\\ b,-2,06+1,73=-0,33\\ c,\left(-5,17\right)\cdot3,1=-16,027\\ d,\left(-9,18\right):4,25=-2,16\)