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

Toán Lớp 8: Phân tích đa thức hành nhân tử x^3(x-y)+4x(y-x) 2/ x^2-8x+15 3/ x^2-y^2+10x+8y+9

Toán Lớp 8: Phân tích đa thức hành nhân tử
x^3(x-y)+4x(y-x)
2/ x^2-8x+15
3/ x^2-y^2+10x+8y+9

Comments ( 2 )

  1. Giải đáp:
     1, x(x – 2)(x + 2)(x – y)
    2, (x – 5)(x – 3)
    3, (x – y + 9)(x + y + 1)
    Lời giải và giải thích chi tiết:
     1, x^3(x -y) + 4x(y – x)
    = x^3(x – y) – 4x(x – y)
    = x(x^2 – 4)(x – y)
    = x(x – 2)(x + 2)(x – y)
    2, x^2 – 8x + 15
    = x^2 – 3x – 5x + 15
    = x(x – 3) – 5(x – 3)
    = (x – 5)(x – 3)
    3, x^2 – y^2 + 10x + 8y + 9
    = x^2 – y^2 + 10x + 8y + 25 – 16
    = (x^2 + 10x + 25) -(y^2 – 8y + 16)
    = (x + 5)^2 – (y – 4)^2
    = (x + 5 – y + 4)(x + 5 + y – 4)
    = (x – y + 9)(x + y + 1)

  2. x^3(x-y)+4x(y-x)
    =x^3(x-y)-4x(x-y)
    =(x-y)(x^3-4x)
     ______________________
    x^2-8x+15
    =(x-4x)^2-1^2
    =(x-4-1)(x-4+1)
    =(x-3)(x-5)
    _______________________
    x^2-y^2+10x+8y+9
    =x^2-y^2+9x+x+9y-y+9
    =(x^2-y^2)+(x-y)+(9x+9y+9)
    =(x+y)(x-y)+(x-y)+9(x+y+1)
    =(x-y)(x+y+1)+9(x+y+1)
    =(x+y+1)(x-y+9)

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