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

Toán Lớp 8: tính x+3/x^2-4 nhân 8-12x+6x^2-x^3/9x +27

Toán Lớp 8: tính
x+3/x^2-4 nhân 8-12x+6x^2-x^3/9x +27

Comments ( 2 )

  1. Giải đáp:
    \frac{x+3}{x^2-4}xx\frac{8-12x+6x^2-x^3}{9x+27}
    = \frac{x+3}{(x-2)(x+2)}xx\frac{(2-x)^3}{9(x+3)}
    = \frac{1}{(x-2)(x+2)}xx\frac{[-(x-2)]^3}{9}
    = \frac{1}{(x-2)(x+2)}xx\frac{-(x-2)^3}{9}
    = \frac{1}{x+2}xx\frac{-(x-2)^3}{9}
    = -\frac{(x-2)^3}{9(x+2)}
    = -\frac{x^2-4x+4}{9x+18}

  2. Lời giải và giải thích chi tiết:
    (x+3)/(x^2-4) . (8-12x+6x^2-x^3)/(9x+27) 
    =(x+3)/((x-2)(x+2)) . ((2-x)^3)/(9(x+3))
    =(-(x+3)(x-2)^3)/(9(x-2)(x+2)(x+3))
    =(-(x-2)^2)/(9(x+2))
    =-(x^2-4x+4)/(9x+18)

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

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