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\(\frac{1}{4}.\frac{15}{49}-\left(\frac{4}{5}+\frac{2}{3}\right)\div3\frac{2}{3}\)
\(=\frac{15}{196}-\left(\frac{12}{15}+\frac{10}{15}\right)\div\frac{11}{3}\)
\(=\frac{15}{196}-\left(\frac{12}{15}+\frac{10}{15}\right).\frac{3}{11}\)
\(=\frac{15}{196}-\frac{22}{15}.\frac{3}{11}\)
\(=\frac{15}{196}-\frac{2}{5}.\frac{1}{1}\)
\(=\frac{15}{196}-\frac{2}{5}\)
\(=\frac{75}{980}-\frac{392}{980}=\frac{-317}{980}\)
\(\frac{1}{4}\cdot\frac{15}{49}-\left(\frac{4}{5}+\frac{2}{3}\right):3\frac{2}{3}\)
\(=\frac{15}{196}-\frac{22}{15}\cdot\frac{3}{11}\)
\(=\frac{15}{196}-\frac{2}{5}\)
\(=-\frac{317}{980}\)
35 + 3.[40 - (5 - 2)2 ]
= 35 + 3.[40 - 32]
= 35 + 3. [40 - 9]
= 35 + 3 x 31
= 35 + 93
= 128
\(\frac{0,4-\frac{2}{9}+\frac{2}{11}}{1,4-\frac{7}{9}+\frac{7}{11}}-\frac{\frac{1}{3}-0,25+\frac{1}{5}}{1\frac{1}{6}-0,875+0,7}\)
\(=\frac{\frac{2}{5}-\frac{2}{9}+\frac{2}{11}}{\frac{7}{5}-\frac{7}{9}+\frac{7}{11}}-\frac{\frac{2}{6}-\frac{2}{8}+\frac{2}{10}}{\frac{7}{6}-\frac{7}{8}+\frac{7}{10}}\)
\(=\frac{2.\left(\frac{1}{5}-\frac{1}{9}+\frac{1}{11}\right)}{7.\left(\frac{1}{5}-\frac{1}{9}+\frac{1}{11}\right)}-\frac{2.\left(\frac{1}{6}-\frac{1}{8}+\frac{1}{10}\right)}{7.\left(\frac{1}{6}-\frac{1}{8}+\frac{1}{10}\right)}\)
\(=\frac{2}{7}-\frac{2}{7}\)
\(=0\)
\(\frac{0,4-\frac{2}{9}+\frac{2}{11}}{1,4-\frac{7}{9}+\frac{7}{11}}-\frac{\frac{1}{3}-0,25+\frac{1}{5}}{1\frac{1}{6}-0,875+0,7}=\frac{\frac{2}{5}-\frac{2}{9}+\frac{2}{11}}{\frac{7}{5}-\frac{7}{9}+\frac{7}{11}}-\frac{\frac{1}{3}-\frac{1}{4}+\frac{1}{5}}{\frac{7}{6}-\frac{7}{8}+\frac{7}{10}}\)
\(=\frac{2\left(\frac{1}{5}-\frac{1}{9}+\frac{1}{11}\right)}{7\left(\frac{1}{5}-\frac{1}{9}+\frac{1}{11}\right)}-\frac{\frac{1}{3}-\frac{1}{4}+\frac{1}{5}}{\frac{7}{2}\left(\frac{1}{3}-\frac{1}{4}+\frac{1}{5}\right)}\)
\(=\frac{2}{7}-\frac{1}{\frac{7}{2}}\)
\(=\frac{2}{7}-\frac{2}{7}=0\)
Study well ! >_<
Đáp án:
Giải thích các bước giải:
1-2+3-4+5-6+... + 2009 - 2010 + 2011
=(1-2)+(3-4)+(5-6)+...+(2009-2010)+2011
=[(-1)+(-1)+(-1)+...+(-1)]+2011
=(-1005)+2011
=1006
Ta có: \(1-2+3-4+5-6+...+2009-2010+2011\)
\(=\left(1-2\right)+\left(3-4\right)+\left(5-6\right)+...+\left(2009-2010\right)+2011\)
\(=\left(-1\right)+\left(-1\right)+\left(-1\right)+...+\left(-1\right)+2011\)
\(=-1005+2011\)
\(=1006\)
`(-1,4):(-3)+5,8:(-3)`
`=(-1,4+5,8):(-3)`
`=4,4:(-3)`
`=-22/15`
\(\left(-1,4\right):\left(-3\right)+\left(5,8\right):\left(-3\right)\)
\(=-1,4\times\left(-\dfrac{1}{3}\right)+5,8\times\left(-\dfrac{1}{3}\right)\)
\(=\left(-\dfrac{1}{3}\right)\times\left(-1,4+5,8\right)\)
\(=\left(-\dfrac{1}{3}\right)\times4,4\)
\(=-\dfrac{22}{15}\)