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

Toán Lớp 8: Tìm x : (4-3x)^2 +9x^2-16 = ( 3x-4)(x+1) ( Ai giúp em với ạ )

Toán Lớp 8: Tìm x :
(4-3x)^2 +9x^2-16 = ( 3x-4)(x+1)
( Ai giúp em với ạ )

Comments ( 2 )

  1. Giải đáp:
    x = 1/5 hoặc x = 4/3
    Giải thích:
    (4 – 3x)^2 + 9x^2 – 16 = (3x – 4)(x + 1)
    => 16 – 24x + 9x^2 + 9x^2 – 16 = 3x^2 – x – 4
    => 18x^2 – 24x – 3x^2 + x + 4 = 0
    => 15x^2 – 23x + 4 = 0
    => 15x^2 – 3x – 20x + 4 = 0
    => 3x(5x – 1) – 4(5x – 1) = 0
    => (5x – 1)(3x – 4) = 0
    => $\left[ \begin{array}{l}5x-1=0\\3x-4=0\end{array} \right.$
    => $\left[ \begin{array}{l}5x=1\\3x=4\end{array} \right.$
    => $\left[ \begin{array}{l}x=\dfrac{1}{5}\\x=\dfrac{4}{3}\end{array} \right.$
    Vậy x = 1/5 hoặc x = 4/3

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