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

Toán Lớp 8: Rút gọn biểu thức B , biết B= ($\frac{x-2}{x+2}$ – $\frac{6x-4}{4-x^2}$) : $\frac{x+1}{x-2}$

Toán Lớp 8: Rút gọn biểu thức B , biết B= ($\frac{x-2}{x+2}$ – $\frac{6x-4}{4-x^2}$) : $\frac{x+1}{x-2}$

Comments ( 2 )

  1. Giải đáp:
     B=(x)/(x+1)
    Lời giải và giải thích chi tiết:
     B=((x-2)/(x+2)-(6x-4)/(4-x^2)):(x+1)/(x-2) (ĐKXĐ:x\ne±2;x\ne-1)
     B=[(x-2)/(x+2)+(6x-4)/((x+2)(x-2))]. (x-2)/(x+1)
     B=[((x-2)^2)/((x+2)(x-2))+(6x-4)/((x+2)(x-2))]. (x-2)/(x+1)
     B=((x-2)^2+6x-4)/((x+2)(x-2)). (x-2)/(x+1)
     B=(x^2-4x+4+6x-4)/((x+2)(x-2)). (x-2)/(x+1)
     B=(x^2+2x)/((x+2)(x-2)). (x-2)/(x+1)
     B=(x(x+2))/((x+2)(x-2)). (x-2)/(x+1)
     B=(x(x+2)(x-2))/((x+2)(x-2)(x+1))
     B=(x)/(x+1)
    Vậy  B=(x)/(x+1)

  2. Gửi bạn:
    $ĐKXĐ:x\neq 2;-2;1-1$
    $B=(\dfrac{x-2}{x+2}-\dfrac{6x-4}{4-x^2}):\dfrac{x+1}{x-2}$ 
    $B=(\dfrac{x-2}{x+2}+\dfrac{6x-4}{x^2-4}):\dfrac{x+1}{x-2}$ 
    $B=(\dfrac{x-2}{x+2}+\dfrac{6x-4}{(x-2)(x+2)}):\dfrac{x+1}{x-2}$ 
    $B=(\dfrac{(x-2)(x-2)}{(x+2)(x-2)}+\dfrac{6x-4}{(x-2)(x+2)}):\dfrac{x+1}{x-2}$ 
    $B=(\dfrac{x^2-4x+4}{(x+2)(x-2)}+\dfrac{6x-4}{(x-2)(x+2)}).\dfrac{x-2}{x+1}$ 
    $B=\dfrac{x^2-4x+4+6x-4}{(x+2)(x-2)}.\dfrac{x-2}{x+1}$ 
    $B=\dfrac{x^2+2x}{(x+2)(x-2)}.\dfrac{x-2}{x+1}$ 
    $B=\dfrac{x(x+2)}{(x-2)(x+2)}.\dfrac{x-2}{x+1}$ 
    $B=\dfrac{x}{1}.\dfrac{1}{x+1}$ 
    $B=\dfrac{x}{x+1}$ 

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