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

Toán Lớp 7: (x – 2021)^2 + (y + 2020)^2= 0

Toán Lớp 7: (x – 2021)^2 + (y + 2020)^2= 0

Comments ( 2 )

  1. (x-2021)^2+(y-2020)^2=0
    Ta thấy: 
    $\begin{cases} (x-2021)^2\geq0∀x\\(y+2020)^2\geq0∀y \end{cases}$
    Dấu = xảy ra khi và chỉ khi:
    $\begin{cases} x-2021=0\\y+2020=0 \end{cases}$⇒$\begin{cases} x=2021\\y=-2020\end{cases}$
    Vậy x=2021 và y=-2020
     

  2. Bạn kham khảo
    (x-2021)^2+(y+2020)^2=0
    Nhận xét:
    (x-2021)^2>=0 AA x
    (y+2020)^2>=0 AA y
    Nên (x-2021)^2+(y+2020)^2>=0 AA x,y
    Dấu “=” xảy ra khi 
    {((x-2021)^2=0),((y+2020)^2=0):}
    <=>{(x-2021=0),(y+2020=0):}
    <=>{(x=2021),(y=-2020):}
    Vậy (x;y)=(2021;-2020)

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