Giá trị biểu thức A = √ ( − 5 )^2/ 10 + √ 9 /15 − √ 81 /2 + √ ( − 8 )^2/ 10 là

21/45

Giá trị biểu thức\[A = \frac{{\sqrt {{{\left( { - 5} \right)}^2}} }}{{10}} + \frac{{\sqrt 9 }}{{15}} - \frac{{\sqrt {81} }}{2} + \frac{{\sqrt {{{\left( { - 8} \right)}^2}} }}{{10}}\] là

\[A = 1\].

\[A = 0\].

\[A = - 2\].

\[A = - 3\].

Giải thích

Chọn D

Ta có: \[A = \frac{{\sqrt {{{\left( { - 5} \right)}^2}} }}{{10}} + \frac{{\sqrt 9 }}{{15}} - \frac{{\sqrt {81} }}{2} + \frac{{\sqrt {{{\left( { - 8} \right)}^2}} }}{{10}}\]

\[ = \frac{5}{{10}} + \frac{3}{{15}} - \frac{9}{2} + \frac{8}{{10}}\]

\[ = \frac{1}{2} + \frac{1}{5} - \frac{9}{2} + \frac{4}{5}\]

\[ = \left( {\frac{1}{2} - \frac{9}{2}} \right) + \left( {\frac{1}{5} + \frac{4}{5}} \right) = - 4 + 1 = - 3\].

Vậy \[A = - 3\].