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

Toán Lớp 8: a)(x – 3)2 – (x + 2)(x – 1) = 0 , b)7x(x – 2) = x2 – 4 em vote 5 sao và ctlhn cho ạ

Tháng Hai 2, 2023 Toán học 1 Comment 0 views

Toán Lớp 8: a)(x – 3)2 – (x + 2)(x – 1) = 0 , b)7x(x – 2) = x2 – 4 em vote 5 sao và ctlhn cho ạ

Comments ( 1 )

  1. truongthanhhung
    truongthanhhung
    2 Tháng Hai, 2023 at 4:28 sáng
    Reply
    a)
    (x-3)^2-(x+2).(x-1)=0
    =>x^2-2.x.3+3^2-(x.x-1.x+2.x-2.1)=0
    =>x^2-6x+9-x^2+x-2x+2=0
    =>(x^2-x^2)-(6x+2x)+9+2=0
    =>0-8x+11=0
    =>-8x=0-11
    =>-8x=-11
    =>x=\frac{11}{8}
    Vậy x=\frac{11}{8}
    $\\$
    b)
    7x.(x-2)=x^2-4
    =>7x.(x-2)=x^2-2^2
    =>7x.(x-2)=(x-2).(x+2)
    =>7x.(x-2)-(x-2).(x+2)=0
    =>(x-2).[7x-(x+2)]=0
    =>(x-2).(7x-x-2)=0
    =>(x-2).(6x-2)=0
    =>\(\left[ \begin{array}{l}x-2=0\\6x-2=0\end{array} \right.\) 
    => \(\left[ \begin{array}{l}x=2\\6x=2\end{array} \right.\) 
    =>\(\left[ \begin{array}{l}x=2\\x=\dfrac{2}{6}\end{array} \right.\) 
    =>\(\left[ \begin{array}{l}x=2\\x=\dfrac{1}{3}\end{array} \right.\) 
    Vậy x=2; x=\frac{1}{3}
     

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

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