Tìm: \(\left| { - {\rm{ }}2{\rm{ }}022} \right|;{\rm{ }}\left| {\sqrt {312} } \right|;{\rm{ }}\left| { - \sqrt {5,4} } \right|;{\rm{ }}\left| {\dfrac{{ - 273}}{3}} \right|;{\rm{ }}\left| { - 20,21} \right|\).
Với mỗi số thực x ta có:
\(\left| x \right| = \left\{ \begin{array}{l}x{\rm{ }}(x \ge 0)\\ - x{\rm{ }}(x < 0)\end{array} \right.\)
Chú ý: \(|x| \ge 0\) với mọi \( x\)
\(\left| { - {\rm{ }}2{\rm{ }}022} \right| = - {\rm{ }}( - {\rm{ }}2{\rm{ }}022) = 2{\rm{ }}022\);
\(\left| {\sqrt {312} } \right| = \sqrt {312}\);
\(\left| { - \sqrt {5,4} } \right| = - {\rm{ }}\left( { - \sqrt {5,4} } \right) = \sqrt {5,4} \);
\(\left| {\dfrac{{ - 273}}{3}} \right| = - \left( {\dfrac{{ - 273}}{3}} \right) = \dfrac{{273}}{3}\);
\(\left| { - 20,21} \right| = - {\rm{ }}( - 20,21) = 20,21\).