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

Toán Lớp 8: Tìm x biết a) (x^2+1) (x-2)+2x-4=0 b) x^4-16x^2=0 Giúp mình với ạ cần gấp

Toán Lớp 8: Tìm x biết
a) (x^2+1) (x-2)+2x-4=0
b) x^4-16x^2=0
Giúp mình với ạ cần gấp

Comments ( 1 )

  1. a)(x^2+1)(x-2)+2x-4=0
    =>(x^2+1)(x-2)+2(x-2)=0
    =>(x-2)(x^2+3)=0
    =>x=2 
    Vậy x=2
    b)x^4-16x^2=0
    =>x^4-8x^2-8x^2+64=0
    =>x^2(x^2-8)-8(x^2-8)=0
    =>(x^2-8)^2=0
    =>$\left[\begin{matrix}x^2-8=8\\ x^2-8=-8\end{matrix}\right.$
    =>$\left[\begin{matrix} x^2=16\\ x^2=0\end{matrix}\right.$
    =>$\left[\begin{matrix} x=+-4\\ x=0\end{matrix}\right.$
    Vậy x={4; -4; 0}

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