so sánh 1/31+1/32+…+1/60 với 1/2 1tieens nx e thi rồi

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so sánh 1/31+1/32+…+1/60 với 1/2 1tieens nx e thi rồi

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Vivian 2 tháng 2021-10-04T04:56:20+00:00 2 Answers 3 views 0

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    0
    2021-10-04T04:57:42+00:00

    Đáp án:

     

    Giải thích các bước giải:

     Ta có: $\dfrac{1}{31}>\dfrac{1}{60}$ $;$ $\dfrac{1}{32}>\dfrac{1}{60}$ $;…;$ $\dfrac{1}{60}=\dfrac{1}{60}$

    $ $

    $⇒\dfrac{1}{31}+\dfrac{1}{32}+…+\dfrac{1}{60}>\dfrac{1}{60}+\dfrac{1}{60}+…+\dfrac{1}{60}$

    $ $

    $⇒\dfrac{1}{31}+\dfrac{1}{32}+…+\dfrac{1}{60}>\dfrac{30}{60}=\dfrac{1}{2}$

    $ $

    $⇒\dfrac{1}{31}+\dfrac{1}{32}+…+\dfrac{1}{60}>\dfrac{1}{2}$

    0
    2021-10-04T04:57:44+00:00

    Ta có:$\frac{1}{31}$+$\frac{1}{32}$+….+  $\frac{1}{60}$ 

    ⇒$\frac{1}{31}$<$\frac{1}{60}$ 

      $\frac{1}{32}$< $\frac{1}{60}$   Có 30 số $\frac{1}{60}$ 

       ……

      $\frac{1}{60}$=$\frac{1}{60}$ 

    ⇒$\frac{1}{31}$+$\frac{1}{32}$+….+  $\frac{1}{60}$<30×$\frac{1}{60}$=$\frac{1}{2}$

    Vậy $\frac{1}{31}$+$\frac{1}{32}$+….+  $\frac{1}{60}$<$\frac{1}{2}$

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