A= 2021×2021+2020/2021×2021+2021 và B= 2021×2021+2021/2021×2021+2022 Giải theo lớp 5 ạ , mong mọi người không cho những kí tự từ lp 6 trở lên . Cam ơm

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A= 2021×2021+2020/2021×2021+2021 và B= 2021×2021+2021/2021×2021+2022
Giải theo lớp 5 ạ , mong mọi người không cho những kí tự từ lp 6 trở lên . Cam ơm

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Adeline 3 tuần 2021-07-09T23:01:57+00:00 2 Answers 5 views 0

Answers ( )

    0
    2021-07-09T23:03:10+00:00

    Đáp án:`A<B`.

     

    Giải thích các bước giải:

    `A=(2021xx2021+2020)/(2021xx2021+2021)`

    `=(2021xx2021+2021-1)/(2021xx2021+2021)`

    `=1-1/(2021xx2021+2021)`

    `B=(2021xx2021+2021)/(2021xx2021+2022)`

    `=(2021xx2021+2022-1)/(2021xx2021+2022)`

    `=1-1/(2021xx2021+2022)`

    Vì `2021<2022`

    Nên `2021xx2021+2021<2021xx2021+2022`

    Suy ra `1/(2021xx2021+2021)>1/(2021xx2021+2022)`

    Suy ra `1-1/(2021xx2021+2021)<1-1/(2021xx2021+2022)`

    Hay `A<B`.

    0
    2021-07-09T23:03:49+00:00

    \(A=\dfrac{2021 \times 2021 + 2020}{2021 \times 2021 + 2021} = \dfrac{2021 \times 2021 + 2021 – 1}{2021 \times 2021 + 2021} \\= 1 – \dfrac{1}{2021 \times 2021+2021} \\ B=\dfrac{2021 \times 2021+2021}{2021 \times 2021 + 2022}=\dfrac{2021 \times 2021+2022-1}{2021 \times 2021 + 2022}\\= 1 – \dfrac{1}{2021 \times 2021+2022} \\\text{Mà} \ 2021 \times 2021 + 2021 < 2021 \times 2021 + 2022 \\ \to \dfrac{1}{2021 \times 2021 + 2021} > \dfrac{1}{2021 \times 2021 + 2022} \\ \to -\dfrac{1}{2021 \times 2021 + 2021} < -\dfrac{1}{2021 \times 2021 + 2022} \\ \to 1-\dfrac{1}{2021 \times 2021 + 2021} < 1-\dfrac{1}{2021 \times 2021 + 2022} \\ \text{Hay A < B}\)

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