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

Toán Lớp 7: Mn ơi , me đang cần gấp ạ :< Tìm x : (x/2)-(1/x)=1/12

Toán Lớp 7: Mn ơi , me đang cần gấp ạ :< Tìm x : (x/2)-(1/x)=1/12

Comments ( 2 )

  1. text{đkxđ}   x \ne 0
    x/2 -1/x = 1/12
    => x.6x – 1.12 = 1.x
    => 6x^2 – 12 = x
    => 6x^2 – x -12=0
    => 6x^2 + 8x – 9x -12=0
    => 2x(3x+4) – 3(3x+4)=0
    => (3x+4)(2x-3)=0
    =>$\left[\begin{matrix} 3x+4=0\\ 2x-3=0\end{matrix}\right.$
    =>$\left[\begin{matrix} x=\dfrac{-4}{3}\\ x=\dfrac{3}{2}\end{matrix}\right.$
    ~~~~~~~~~~~GOOD LUCK~~~~~~~~
     

  2. Tìm x : x/2 – 1/x=1/12
    x/2 – 1/x = 1/12 $( ĐK:$ x ne 0)
    => x/2 – 1/x – 1/12 = 0
    => (6x^2)/(12x) – 12/(12x) – x/(12x) = 0
    => (6x^2 – 12x -x)/(12x) = 0
    => (6x^2 – 12 – 9x +8x)/(12x) = 0
    => (6x^2 – 9x + 8x – 12)/(12x) = 0
    => 6x^2 – 9x + 8x – 12 = 0
    => 3x(2x – 3) + 4(2x – 3) = 0
    => (3x + 4)(2x-3) = 0
    => $\left[\begin{matrix} 3x+4 = 0\\ 2x – 3 = 0\end{matrix}\right.$
    => $\left[\begin{matrix} 3x = -4\\ 2x = 3\end{matrix}\right.$
    => $\left[\begin{matrix} x= \dfrac{-4}{3} \\x=\dfrac{3}{2} \end{matrix}\right.$

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