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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 7: So sánh A=2021^2021+2 /2021^2022+2 và B=2021^2019+2 /2021^2020+2

Toán Lớp 7: So sánh A=2021^2021+2 /2021^2022+2 và B=2021^2019+2 /2021^2020+2

Comments ( 1 )

  1. Giải đáp:
    $A<B.$
    Lời giải và giải thích chi tiết:
    $A=\dfrac{2021^{2021}+2}{2021^{2022}+2}, B=\dfrac{2021^{2019}+2}{2021^{2020}+2}\\ 2021A=\dfrac{2021(2021^{2021}+2)}{2021^{2022}+2}=\dfrac{2021^{2022}+4042}{2021^{2022}+2}=1+\dfrac{4040}{2021^{2022}+2}\\ 2021B=\dfrac{2021(2021^{2019}+2)}{2021^{2020}+2}=\dfrac{2021^{2020}+4042}{2021^{2020}+2}=1+\dfrac{4040}{2021^{2020}+2}\\ \text{Do }2021^{2022}+2>2021^{2020}+2\\ \Rightarrow \dfrac{4040}{2021^{2022}+2}<\dfrac{4040}{2021^{2020}+2}\\ \Rightarrow 1+\dfrac{4040}{2021^{2022}+2}<1+\dfrac{4040}{2021^{2020}+2}\\ \Leftrightarrow 2021A<2021B\\ \Leftrightarrow A<B.$

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222-9+11+12:2*14+14 = ? ( )

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