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

Toán Lớp 7: tìm x 2/3-1/3(x-3/2)-1/2(2x+1)=5 (x+1/2).(x-3/4)=0 lưu ý 3/4 là 3 phần 4 . là nhân giải dùm em vs ạ, cảm ơn

Toán Lớp 7: tìm x
2/3-1/3(x-3/2)-1/2(2x+1)=5
(x+1/2).(x-3/4)=0
lưu ý 3/4 là 3 phần 4
. là nhân
giải dùm em vs ạ, cảm ơn

Comments ( 2 )

  1. $\frac{2}{3}-\frac{1}{3}(x-\frac{3}{2})-\frac{1}{2}(2x+1)=5$
    ⇔$\frac{2}{3}-\frac{x}{3}+\frac{1}{2}-x-\frac{1}{2}=5$
    ⇔$\frac{2-x}{3}-x=5$
    ⇔$\frac{2-x-3x}{3}=\frac{15}{3}$
    ⇔$\frac{2-4x}{3}=\frac{15}{3}$
    ⇔$2-4x=15$
    ⇔$-4x=13$
    ⇔$x=-13/4$
    $(x+\frac{1}{2}).(x-\frac{3}{4})=0$
    ⇔\(\left[ \begin{array}{l}x+\frac{1}{2}=0\\x-\frac{3}{4}=0\end{array} \right.\) ⇔\(\left[ \begin{array}{l}x=-\frac{1}{2}\\x=\frac{3}{4}\end{array} \right.\)

  2. a)
    2/3-1/3(x-3/2)-1/2(2x+1)=5
    \to 2/3-1/3x+1/2-x-1/2=5
    \to (-1/3x-x)+(2/3+1/2-1/2)=5
    \to -4/3x+2/3=5
    \to -4/3x=5-2/3
    \to -4/3x=13/3
    \to x=13/3:(-4/3)
    \to x=-13/4
    Vậy x=-13/4
    b)
    (x+1/2)(x-3/4)=0
    \to \(\left[ \begin{array}{l}x+\dfrac{1}{2}=0\\x-\dfrac{3}{4}=0\end{array} \right.\) \to \(\left[ \begin{array}{l}x=-\dfrac{1}{2}\\x=\dfrac{3}{4}\end{array} \right.\) 
    Vậy x\in{3/4;-1/2}

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