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

Toán Lớp 8: Rút gọn( tìm đkxđ )A=(x+1/x-1 / x-1/x+1):2x/5x-5

Toán Lớp 8: Rút gọn( tìm đkxđ )A=(x+1/x-1 / x-1/x+1):2x/5x-5

Comments ( 2 )

  1. #Sad
    A= ((x+1)/(x-1)+(x-1)/(x+1)) : (2x)/(5x-5)
    \text{ĐKXĐ:} {(2x \ne 0),(x+-1 \ne 0),(5x-5 \ne 0):}
    ⇒ {(x \ne 0),(x \ne +-1):}
    A= ((x+1)/(x-1)+(x-1)/(x+1)) : (2x)/(5x-5)
    = ((x+1)^2)/((x-1)(x+1))+((x-1)^2)/((x-1)(x+1)) : (2x)/(5x-5)
    = (x^2+2x+1+x^2-2x+1)/((x+1)(x-1)) : (2x)/(5x-5)
    = (2x^2+2)/((x+1)(x-1)) . (5(x-1))/(2x)
    = (2(x^2+1))/((x+1)(x-1)). (5(x-1))/(2x)
    = (5(x^2+1))/x(x+1)
    = (5x^2+5x)/(x^2+x)

  2. Lời giải và giải thích chi tiết:
    ĐKXĐ : x ne 0;+-1
    A=((x+1)/(x-1)+(x-1)/(x+1)):(2x)/(5x-5) 
    =((x+1)^2+(x-1)^2)/((x+1)(x-1)).(5(x-1))/(2x)
    =(x^2+2x+1+x^2-2x+1)/(x+1) . 5/(2x)
    =(2x^2+2)/(x+1) . 5/(2x)
    =(2(x^2+1))/(x+1) . 5/(2x)
    =(5(x^2+1))/(x(x+1))=(5x^2+5)/(x^2+x)

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