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

Toán Lớp 8: tim x 2x ( x-2 ) – (2-x)^2 =0

Toán Lớp 8: tim x
2x ( x-2 ) – (2-x)^2 =0

Comments ( 2 )

  1. Ta có :
    2x(x-2) – (2-x)^2 =0
    -> 2x(x-2) – (x-2)^2 =0
    -> (x-2)(2x – x+ 2) =0
    ->  (x-2)(x+2) =0
    -> x- 2 =0 hoặc x +2 =0
    -> x = 2 hoặc x =-2
    Vậy x \in {2 ; -2}

  2. 2x(x-2) – (2-x)^2 = 0
    <=> 2x(x-2) – (x-2)^2 = 0
    <=> [2x- (x-2)](x-2) = 0
    <=> [2x – x + 2](x-2) = 0
    <=> (x + 2)(x-2) = 0
    <=> \(\left[ \begin{array}{l}x-2=0\\x+2 =0 \end{array} \right.\) 
    <=> \(\left[ \begin{array}{l}x=2\\x=-2\end{array} \right.\) 
    Vậy x ∈ {2;-2}

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