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

Toán Lớp 8: quy đồng phân thức (x+2)/(x^3+1);(4-x)/(x^2+2x+1)

Toán Lớp 8: quy đồng phân thức
(x+2)/(x^3+1);(4-x)/(x^2+2x+1)

Comments ( 2 )

  1. (x+2)/(x^3 + 1)
    = ((x+2)(x+1))/( (x+1)^2 (x^2 -x+1))
    = (x^2+ x + 2x +2)/( (x+1)^2 (x^2 – x+1))
    = (x^2+  3x+2)/((x+1)^2 (x^2 – x+1))
    (4-x)/(x^2 + 2x+1)
    = ((4-x)(x^2 – x +1))/((x+1)^2 (x^2 – x+1))
    = (4x^2 -4x + 4 – x^3 + x^2 – x )/((x+1)^2 (x^2 – x+1))
    =  ( 5x^2 – x^3 – 5x + 4)/((x+1)^2 (x^2 – x+1))
     

  2. Giải đáp+Lời giải và giải thích chi tiết:
    (x+2)/(x^3+1)
    =(x+2)/((x+1)(x^2-x+1))
    (4-x)/(x^2+2x+1)
    =(4-x)/(x+1)^2
    => Mẫu chung:(x+1)^2(x^2-x+1)
    =>(x+2)/((x+1)(x^2-x+1))=((x+2)(x+1))/((x+1)^2(x^2-x+1))=(x^2+3x+2)/((x+1)^2(x^2-x+1))
    (4-x)/(x+1)^2=((4-x)(x^2+x+1))/((x+1)^2(x^2-x+1))=(4x^2+4x+4-x^3-x^2-x)/((x+1)^2(x^2-x+1))=(-x^3+3x^2+3x+4)/((x+1)^2(x^2-x+1))

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

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