a) 2x^2y^2(x^3y^2-x^2y^3-1/2y^5) b) -1/3xy(3x^3y^2-6x^2+y^2) c) (-2xy^2+2/3y^2+4xy^2).3/2xy d) (x^2+2xy-3)(-xy) e) 1/2x^2y(2x^3-2/5xy^2-1) f) (-xy^2)^2.(x^2-2x+1)

Đáp án + Giải thích các bước giải :

`a, 2x^2y^2 * ( x^3y^2 - x^2y^3 - 1/2y^5 )`

`= 2x^2y^2 * x^3y^2 - 2x^2y^2 * x^2y^3 - 2x^2y^2 * 1/2y^5`

`= 2x^5y^4 - 2x^4y^5 - x^2y^7` .

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`b, - 1/3xy * ( 3x^3y^2 - 6x^2 + y^2 )`

`= - 1/3xy * 3x^3y^2 - 1/3xy * ( - 6x^2 ) - 1/3xy * y^2 `

`= - x^4y^3 + 2x^3y - 1/3xy^3` .

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`c, ( - 2xy^2 + 2/3y^2 + 4xy^2 ) * 3/2xy`

`= - 2xy^2 * 3/2xy + 2/3y^2 * 3/2xy + 4xy^2 * 3/2xy`

`= - 3x^2y^3 + xy^3 + 6x^2y^3`

`= ( 6x^2y^3 - 3x^2y^3 ) + xy^3`

`= 3x^2y^3 + xy^3` .

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`d, ( x^2 + 2xy - 3) * ( - xy )`

`= x^2 * ( - xy ) + 2xy * ( - xy ) - 3 * ( - xy )`

`= - x^3y - 2x^2y^2 + 3xy` .

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`e, 1/2x^2y * ( 2x^3 - 2/5xy^2 - 1 )`

`= 1/2x^2y * 2x^3 - 1/2x^2y * 2/5xy^2 - 1/2x^2y * 1`

`= x^5y - 1/5x^3y^3 - 1/2x^2y` .

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`f, ( - xy^2 )^2 * ( x^2 - 2x + 1 )`

`= - x^2y^4 * ( x^2 - 2x + 1 )`

`= - x^2y^4 * x^2 - x^2y^4 * ( - 2x ) - x^2y^4 * 1`

`= - x^4y^4 + 2x^3y^4 - x^2y^4` .

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