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Tính :
a) \(\sqrt {{8^2} + {6^2}} \);
b) \(\sqrt {{{\left( {0,3} \right)}^2}} \);
c) \(\sqrt {{{\left( { – 0,3} \right)}^2}} \);
d) \( – 0,2\sqrt {{{\left( { – 0,5} \right)}^2}} \).
Sử dụng công thức: \(\sqrt {{A^2}} = \left| A \right| = \left\{ \begin{array}{l}A\;\;khi\;\;A \ge 0\\ – A\;\;khi\;\;A < 0\end{array} \right..\)
\(\begin{array}{l}a)\;\sqrt {{8^2} + {6^2}} = \sqrt {64 + 36} = \sqrt {100} = 10.\\b)\;\sqrt {{{\left( {0,3} \right)}^2}} = \left| {0,3} \right| = 0,3.\\c)\;\sqrt {{{\left( { – 0,3} \right)}^2}} = \left| { – 0,3} \right| = 0,3.\\d)\; – 0,2\sqrt {{{\left( { – 0,5} \right)}^2}} = – 0,2.\left| { – 0,5} \right| = – 0,2.0,5 = – 0,1.\end{array}\)