.\(\begin{array}{l}a)\,1,75 - \left| x \right| = - 3,21\\ \Leftrightarrow \,\,\,\,\,\,\,\,\,\,\,\,\,\left| x \right| = 1,75 + 3,21\\ \Leftrightarrow \,\,\,\,\,\,\,\,\,\,\,\,\,\left| x \right| = 4,96\\ \Leftrightarrow \left[ \begin{array}{l}x = 4,96\\x = - 4,96\end{array} \right.\end{array}\).
ý b) em làm tương tự nhé