tính hợp lí E=13/30+28/45.5/2-[(1/2+1/3):53/90]:50/53

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1. Đáp án:

    $E=\dfrac{22}{45}$

   Giải thích các bước giải:

    $E=\dfrac{13}{30}+\dfrac{28}{45}.\dfrac{5}{2}-\left [ \left ( \dfrac{1}{2}+\dfrac{1}{3} \right ):\dfrac{53}{90} \right ]:\dfrac{50}{53}\\
   =\dfrac{13}{30}+\dfrac{2.14}{5.9}.\dfrac{5}{2}-\left [ \left ( \dfrac{1}{2}+\dfrac{1}{3} \right ).\dfrac{90}{53} \right ].\dfrac{53}{50}\\
   =\dfrac{13}{30}+\dfrac{14}{9}- \left ( \dfrac{3}{6}+\dfrac{2}{6} \right ).\dfrac{90}{53} .\dfrac{53}{50}\\
   =\dfrac{13}{30}+\dfrac{14}{9}-  \dfrac{5}{6}.\dfrac{9}{5} \\
   =\dfrac{13}{30}+\dfrac{14}{9}-  \dfrac{3}{2} \\
   =\dfrac{13.3}{90}+\dfrac{14.10}{90}-  \dfrac{45.3}{45.2} \\
   =\dfrac{39+140-135}{90}\\
   =\dfrac{44}{90}\\
   =\dfrac{22}{45}$

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