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

Toán Lớp 7: tìm x biết (2x+4/3)(x2+2021)=0

Toán Lớp 7: tìm x biết
(2x+4/3)(x2+2021)=0

Comments ( 2 )

  1. (2x+4/3)(x^2+2021)=0
    ⇔\(\left[ \begin{array}{l}2x+\dfrac{4}{3}=0\\x^2+2021=0\end{array} \right.\) 
    ⇔\(\left[ \begin{array}{l}x=-\dfrac{2}{3}\\x^2=-2021 \text{(vô lý)}\end{array} \right.\) 
    Vậy x=-2/3

  2. $\\$
    Giải đáp + giải thích các bước giải :
    $(2x+\dfrac{4}{3})(x^2 +2021)=0\\\text{Trường hợp 1 :}\\2x+\dfrac{4}{3}=0\\⇒2x=0-\dfrac{4}{3}\\⇒2x=\dfrac{-4}{3}\\⇒x=\dfrac{-4}{3}:2\\⇒x=\dfrac{-2}{3}\\\text{Trường hợp 2 :}\\x^2 +2021=0\\ \text{Nhận xét :}x^2 ≥0∀x\\⇒x^2 +2021 ≥ 2021 \ne 0\\⇒x =∅\\\text{Vậy}x=\dfrac{-2}{3}$
     

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

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