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

Toán Lớp 7: Biết $|3x-4y-2|^{2021}$ + $(x-2y)^{2020}$ =0

Toán Lớp 7: Biết $|3x-4y-2|^{2021}$ + $(x-2y)^{2020}$ =0

Comments ( 1 )

  1. Answer
    Ta có:
    |3x – 4y – 2|^2021 >= 0 AA x , y \in RR
    (x – 2y)^2020 >= 0 AA x , y \in RR
    => |3x – 4y – 2|^2021 + (x – 2y)^2020 >= 0 AA x , y \in RR
    Dấu ‘=’ xảy ra 
    <=> {(3x – 4y – 2 = 0),(x – 2y = 0):}
    <=> {(3x – 4y – 2 = 0),(x = 0 + 2y):}
    <=> {(3x – 4y – 2 = 0),(x = 2y):}
    <=> {(3 . 2y – 4y – 2 = 0),(x = 2y):}
    <=> {(6y – 4y – 2 = 0),(x = 2y):}
    <=> {(2y – 2 = 0),(x = 2y):}
    <=> {(2y = 0 + 2),(x = 2y):}
    <=> {(2y = 2),(x = 2y):}
    <=> {(y = 2 : 2),(x = 2y):}
    <=> {(y = 1),(x = 2y):}
    <=> {(y = 1),(x = 2 . 1):}
    <=> {(y = 1),(x = 2):}
    Vậy (x , y) = (2 , 1)

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

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