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

Toán Lớp 8: a/ -8x(x^2+2)+(2x-1)(4x^2+4x+1)=0 b/ x^2-5x=6 Tìm x nhé bạn

Toán Lớp 8: a/ -8x(x^2+2)+(2x-1)(4x^2+4x+1)=0
b/ x^2-5x=6
Tìm x nhé bạn

Comments ( 1 )

  1. a, – 8x(x^2 + 2) + (2x-1)(4x^2 + 4x +1)=0
    -8x^3 – 16x + 8x^3 – 1=0
    (-8x^3 + 8x^3 ) – 16x -1=0
    -16x-1=0
    => x = -1/16
    b, x^2 – 5x =6
    x^2 – 5x – 6=0
    x^2 + x – 6x -6=0
    x(x+1) – 6(x+1)=0
    (x+1)(x-6)=0
    =>\(\left[ \begin{array}{l}x=-1\\x=6\end{array} \right.\) 
    \text{Vậy} x ∈ { -1;6}
     

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