phaan tichs dda thucws thanhf nhân tử a, 1-2a+2bc+a^2-b^2-c^2 b, -x^3+9x^2-27x+27 c, x^2+4x-y^2+4 d, 16x^3-54y^3

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1. a) `1-2a+2bc+a^2-b^2-c^2`

   `=(a^2-2a+1)-(b^2-2bc+c^2)`

   `=(a-1)^2-(b-c)^2`

   `=(a-1+b-c)(a-1-b-c)`

   b) `-x^3+9x^2-27x+27`

   `=-(x^3-3.x^2 .3 + 3.x.3^2 -3^3)`

   `=-(x-3)^3`

   c) `x^2+4x-y^2+4`

   `=(x^2+4x+4)-y^2`

   `=(x+2)^2-y^2`

   `=(x+2+y)(x+2-y)`

   d) `16x^3-54y^3`

   `=16(x^3-27/8 y)`

   `=16 [x^3 – (3/2y)^3]`

   `=16 (x-3/2y)(x^2+3/2 xy +9/4 y^2)`

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2. Đáp án:

   `downarrow`

   Giải thích các bước giải:

   `a,1-2a+2bc+a^2-b^2-c^2`

   `=a^2-2a+1-(b^2-2bc+c^2)`

   `=(a-1)^2-(b-c)^2`

   `=(a-b+c-1)(a+b-c-1)`

   `b,-x^3+9x^2-27x+27`

   `=(-x)^3+3(-x)^2.3-3.x.9+(3)^3`

   `=(3-x)^3`

   `c,x^2+4x-y^2+4`

   `=(x^2+4x+4)-y^2`

   `=(x+2)^2-y^2`

   `=(x-y+2)(x+y+2)`

   `d,16x^3-54y^3`

   `=2(x^3-27y^3)`

   `=2(x-3y)(x^2+3xy+9y^2)`

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