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

Toán Lớp 8: MẤY BRO GIÚP TỚ NKA . TỚ CKO 5 SAO+CẢM ƠN+HAY NHẤT Ạ d. (x – 2)2 – (x – 3)(x + 3) = 6 e. 4x(x – 3) – 2x + 6 = 0 f. x(

Toán Lớp 8: MẤY BRO GIÚP TỚ NKA . TỚ CKO 5 SAO+CẢM ƠN+HAY NHẤT Ạ
d. (x – 2)2 – (x – 3)(x + 3) = 6 e. 4x(x – 3) – 2x + 6 = 0 f. x(2x – 3) – 2(3 – 2x) = 0

Comments ( 2 )

  1. d) ( x –  2 )^2 – ( x – 3 ) ( x + 3 ) =6
    ⇒ x^2 – 4x + 4 – x^2 + 9 =6
    ⇒ -4x + 13 =6
    ⇒ -4x = -7
    ⇒ x = 7/4
    Vậy x = 7/4
    e) 4x ( x – 3 ) -2x + 6 =0
    ⇒ 4x ( x – 3 ) – 2 ( x – 3 )=0
    ⇒ ( x – 3 ) ( 4x – 2 ) =0
    ⇒ \(\left[ \begin{array}{l}x – 3=0\\4x – 2=0\end{array} \right.\) 
    ⇒ \(\left[ \begin{array}{l}x=3\\x=\dfrac{1}{2}\end{array} \right.\)
    Vậy x ∈ { 3 ; \frac{1}{2} }
    f) x ( 2x – 3) – 2 ( 3 -2x ) =0
    ⇒ x ( 2x – 3 ) + 2 ( 2x – 3 ) =0
    ⇒ ( x + 2 ) ( 2x – 3 ) =0 
    ⇒ \(\left[ \begin{array}{l}x + 2=0\\2x – 3=0\end{array} \right.\) 
    ⇒ \(\left[ \begin{array}{l}x=-2\\x=\dfrac{3}{2}\end{array} \right.\) 
    Vậy x ∈ { -2 ; 3/2 }

  2. d)
    (x-2)^2-(x-3).(x+3)=6
    =>x^2-2x.2+2^2-(x^2-3^2)=6
    =>x^2-4x+4-x^2+9=6
    =>(x^2-x^2)-4x+4=-3
    =>-4x=-7
    =>x=\frac{7}{4}
    Vậy x=\frac{7}{4}
    $\\$
    e)
    4x.(x-3)-2x+6=0
    =>4x.(x-3)-(2x-6)=0
    =>4x.(x-3)-2.(x-3)=0
    =>(x-3).(4x-2)=0
    =>\(\left[ \begin{array}{l}x-3=0\\4x-2=0\end{array} \right.\) 
    =>\(\left[ \begin{array}{l}x=3\\4x=2\end{array} \right.\) 
    =>\(\left[ \begin{array}{l}x=3\\x=\dfrac{2}{4}\end{array} \right.\) 
    =>\(\left[ \begin{array}{l}x=3\\x=\dfrac{1}{2}\end{array} \right.\) 
    Vậy x=3; x=\frac{1}{2}
    $\\$
    f)
    x.(2x-3)-2.(3-2x)=0
    =>x.(2x-3)+2.(2x-3)=0
    =>(2x-3).(x+2)=0
    =>\(\left[ \begin{array}{l}2x-3=0\\x+2=0\end{array} \right.\) 
    =>\(\left[ \begin{array}{l}2x=3\\x=-2\end{array} \right.\) 
    =>\(\left[ \begin{array}{l}x=\dfrac{3}{2}\\x=-2\end{array} \right.\) 
    Vậy x=\frac{3}{2}; x=-2
     

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

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