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

Toán Lớp 8: a) x-12/6x-36 + 6/x*2-6x b) 3-x/x*2-1 + x-1/x*2+x CÁC BẠN GIÚP MÌNH NHÉ!

Toán Lớp 8: a) x-12/6x-36 + 6/x*2-6x
b) 3-x/x*2-1 + x-1/x*2+x
CÁC BẠN GIÚP MÌNH NHÉ!

Comments ( 2 )

  1. Giải đáp:
    a) {x – 6}/{6x}
    b) 1/{x(x-1)}
    Lời giải và giải thích chi tiết:
     a)
    {x – 12}/{6x – 36} + 6/{x^2 – 6x}
    = {x – 12}/{6(x – 6)} + 6/{x(x – 6)}
    = {x(x – 12)}/{6x(x – 6)} + {6.6}/{6x(x – 6)}
    = {x^2 – 12x }/{6x(x – 6)} + {36}/{6x(x – 6)}
    = {x^2 – 12x + 36}/{6x(x – 6)}
    = {x^2 – 2.x.6 + 6^2}/{6x(x – 6)}
    = {(x – 6)^2}/{6x(x – 6)}
    = {x – 6}/{6x}
    b)
    {3 – x}/{x^2 – 1} + {x – 1}/{x^2 + x}
    = {3 – x}/{(x – 1)(x + 1)} + {x – 1}/{x(x + 1)}
    = {x(3 – x)}/{(x – 1)(x + 1)} + {(x – 1)(x-1)}/{x(x + 1)(x-1)}
    = {3x – x^2}/{(x – 1)(x + 1)} + {(x – 1)^2}/{x(x + 1)(x-1)}
    = {3x – x^2}/{(x – 1)(x + 1)} + {x^2 – 2x + 1}/{x(x + 1)(x-1)}
    = {3x – x^2 + x^2 – 2x + 1}/{x(x + 1)(x-1)}
    = {x + 1}/{x(x + 1)(x-1)}
    = 1/{x(x-1)}
    #SunHee

  2. a) (x-12)/(6x-36) + 6/(x^2- 6x) (ĐK: x\ne 0; x\ne 6)
    = (x-12)/(6(x-6)) + 6/(x(x-6))
    = (x(x-12)+ 36)/(6x(x-6))
    = (x^2- 12x+ 36)/(6x(x-6))
    = (x-6)^2/(6x(x-6))
    = (x- 6)/(6x)
    ————
    b) (3-x)/(x^2-1)+(x-1)/(x^2+x) (ĐK: x\ne +-1′ x\ne0)
    = (3-x)/((x-1)(x+1)+ (x-1)/(x(x+1))
    = (x(3-x)+(x-1)^2)/(x(x-1)(x+1))
    = (3x- x^2+ x^2- 2x+ 1)/(x(x^2- 1))
    = (x+1)/(x(x-1)(x+1))
    = 1/(x(x-1))
    = 1/(x^2-x)
     

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

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