…giúp im…………

Question

…giúp im…………
giup-im

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8 tháng 2020-11-02T03:38:14+00:00 2 Answers 52 views 0

Answers ( )

  1. $\dfrac{x-1}{2020}=\dfrac{2021}{x}$

    $↔x(x-1)=2021.2020$

    \(↔\left[ \begin{array}{l}x=2021\\x-1=2020↔x=2021\end{array}↔tm \right.\)

    \(↔\left[ \begin{array}{l}x=2020\\x-1=2021↔x=2022\end{array}↔ktm \right.\)

    $→x=2020$

  2. Đáp án: $x=\{2021,-2020\}$

    Giải thích các bước giải:

    ĐKXĐ: $x\ne 0$

    Nếu $x=-2020\to\dfrac{-2020-1}{2020}=\dfrac{2021}{-2020}$ đúng

    Nếu $x\ne -2020$

    Ta có:

    $\dfrac{x-1}{2020}=\dfrac{2021}{x}=\dfrac{x-1+2021}{2020+x}=\dfrac{x+2020}{x+2020}=1$

    $\to x-1=2020\to x=2021$ 

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