(x+1)^3+(x-2)^3 1-y^3+6xy^2-12x^2y+8x^3 2004^2-16 giúp em với ạ

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1. `(x+1)³+(x-2)³`

   `=[(x+1)+(x-2)][(x+1)²-(x+1)(x-2)+(x-2)²]`

   `=(x+1+x-2)[x²+2x+1-(x²-2x+x-2)+x²-4x+4]`

   `=(2x-1)(x²+2x+1-x²+2x-x+2+x²-4x+4)`

   `=(2x-1)(x²-x+7)`

   `1-y³+6xy²-12x²y+8x³`

   `=1-(y³-6xy²+12x²y-8x³)`

   `=1-[y³-3.y².2x+3.y.(4x)²-(2x)³]`

   `=1-(y-2x)³`

   `=(1-y+2x)[1²+1(y-2x)+(y-2x)²]`

   `=(1-y+2x)(1+y-2x+y²-4xy+4x²)`

   `2004²-16`

   `=2004²-4²`

   `=(2004+4)(2004-4)`

   `=2008.2000`

   `=4016000`

    

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2. `a) (x+1)^3 + (x-2)^3`

   ` = [ (x+1) + (x-2) ] . [ (x+1)^2 – (x+1).(x-2) + (x-2)^2]`

   ` = (x+1+x-2) . [ (x^2  +2x+1) – (x^2 – 2x + x -2) + (x^2 – 4x+4)]`

   ` = (2x – 1) . (x^2 + 2x + 1 – x^2 + 2x – x + 2 + x^2 – 4x + 4)`

   ` = (2x-1) . (x^2 -x+7)`

   `b) 1 – y^3 + 6xy^2 – 12x^2y + 8x^3` 

   ` = 1 – (y^3 – 6xy^2 + 12x^2y – 8x^3)`

   ` = 1 – ( y – 2x)^3`

   ` = [ (1 – ( y-2x)] . [ 1 + y – 2x + (2x-y)^2]`

   ` = (1 – y + 2x) . (1 + y – 2x + y^2 – 4xy + 4x^2)`

   `c) 2004^2 – 16`

   ` = 2004^2 – 4^2`

   `  =(2004 – 4) . (2004+ 4)`

   ` = 2000 . 2008`

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