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

Toán Lớp 7: Tìm các giá trị x thoã mãn |X+2/5| -2=-1/4

Toán Lớp 7: Tìm các giá trị x thoã mãn |X+2/5| -2=-1/4

Comments ( 2 )

  1. |x + $\frac{2}{5}$| – 2 = -$\frac{1}{4}$ 
    |x + $\frac{2}{5}$| = $\frac{7}{4}$ 
    x + $\frac{2}{5}$ = ±$\frac{7}{4}$
    TH1: x + $\frac{2}{5}$ = $\frac{7}{4}$ 
            x = $\frac{27}{20}$ 
    TH2: x + $\frac{2}{5}$ = -$\frac{7}{4}$ 
            x = -$\frac{43}{20}$ 
    Vậy x ∈ {$\frac{27}{20}$; -$\frac{43}{20}$}
    Chúc bạn học tốt
     

  2. #WAB
    $\left|x+\dfrac25 \right| – 2 = -\dfrac14$
    $⇔ \left|x+\dfrac25 \right| = \dfrac74$
    $⇔ x+\dfrac25=\dfrac74$ hoặc $x+\dfrac25 = -\dfrac74$
    $⇔ x=\dfrac{27}{20}$ hoặc $x=-\dfrac{-43}{20}$

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

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