Tính
\(a)\,0,6 + {2 \over { - 3}};\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,b)\,\,{1 \over 3} - \left( { - 0,4} \right)\)
Ta có
a) \(\,0,6 + {2 \over { - 3}} = {6 \over {10}} + {{ - 2} \over 3} = {3 \over 5} + {{ - 2} \over 3}\)
\(\, = {{3.3} \over {5.3}} + {{ - 2.5} \over {3.5}} = {9 \over {15}} + {{ - 10} \over {15}}\)
\( = {{9 - 10} \over {15}} = {{ - 1} \over {15}}\)
b) \({1 \over 3} - \left( { - 0,4} \right) = {1 \over 3} + 0,4 = {1 \over 3} + {4 \over {10}} = {1 \over 3} + {2 \over 5}\)
\( = {{1.5} \over {3.5}} + {{2.3} \over {5.3}} = {5 \over {15}} + {6 \over {15}}\)
\( = {{5 + 6} \over {15}} = {{11} \over {15}}\)