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

Toán Lớp 8: x^5 – 3x^4 + 3x^3 – x^2 2x^2 – 7x -9 8x^3 – 12x^2y + 6xy^2 – y^3

Toán Lớp 8: x^5 – 3x^4 + 3x^3 – x^2
2x^2 – 7x -9
8x^3 – 12x^2y + 6xy^2 – y^3

Comments ( 1 )

  1. Giải đáp+Lời giải và giải thích chi tiết:
    a)  x^5-3x^4+3x^3-x^2
    =(x^5-x^2)-(3x^4-3x^3)
    =x^2(x^3-1)-3x^3(x-1)
    =x^2(x-1)(x^2+x+1)-3x^3(x-1)
    =(x-1)[x^2(x^2+x+1)-3x^3]
    =(x-1)(x^4+x^3+x^2-3x^3)
    =(x-1)(x^4-2x^3+x^2)
    b)  2x^2-7x-9
    =2x^2+2x-9x-9
    =(2x^2+2x)-(9x+9)
    =2x(x+1)-9(x+1)
    =(x+1)(2x-9)
    c)  8x^3-12x^2y+6xy^2-y^3
    =(2x)^3-3.(2x)^2 .y+2.3x.y^2-y^3
    =(2x-y)^3
    -> Áp dụng HĐT: (A-B)^3=A^3-3A^2B+3AB^2-B^3
    $\text{#LinhSad}$

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