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

Toán Lớp 8: Phân tích các đa thức sau thành nhân 1) y^2(x² + y) – zx^2– zy 2) x^3+8+6x(x + 2) 3) (5x-4)^2 -49x^2 4) x^2 – 2xy + y^2 – xz+ yz 5) 3 –

Toán Lớp 8: Phân tích các đa thức sau thành nhân
1) y^2(x² + y) – zx^2– zy
2) x^3+8+6x(x + 2)
3) (5x-4)^2 -49x^2
4) x^2 – 2xy + y^2 – xz+ yz
5) 3 – 9x + 9×2 – 3x^3

Comments ( 2 )

  1. 1) y^2 (x^2 + y ) – zx^2 – zy
    = y^2 (x^2 +y) – z(x^2 + y)
    = (x^2 + y)(y^2 -z)
    2) x^3 + 8 + 6x(x+2)
    = (x+2)(x^2 + 2x + 4) + 6x(x+2)
    =(x+2)(x^2 + 8x + 4)
    3) (5x-4) ^2 – 49x^2
    = (5x-4)^2 – (7x)^2
    = (5x-4+7x)(5x – 4 -7x)
    = (12x – 4)(-2x -4)
    = -8(3x-1)(x+2)
    4) x^2 – 2xy + y^2 – xz +yz
    =(x^2 – 2xy + y^2 ) +(-xz +yz)
    = (x-y)^2 – z(x-y)
    =(x-y)(x-y-z)
    5) 3 -9x + 9x^2 – 3x^3
    = 3( 1 – 3x) – 3x^2 (1 – 3x)
    =(1-3x)(3-3x^2 )

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