Question

Thực hiện phép tính

a) (-xy\(^2\))² . (x\(^2\) - 2x +1)

b) (x + 2y) . (x\(^2\) - 2y +4z)

c) \(\dfrac{27}{15}\)x\(^3\)yz\(^5\) : \(\dfrac{9}{5}\)xz\(^2\)

d) 3x\(^2\)y - 9xy\(^2\) + 12x\(^2\)y\(^2\)

e) x\(^3\) - 6x\(^2\)y + 12xy\(^2\) - 8y\(^3\)

Answer 1

`(-xy^2)^2 . (x^2 - 2x+ 1)`

`= x^2 y^4 . (x^2 - 2x+ 1)`

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

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`(x+2y) . (x^2 - 2y + 4z)`

`= x^3 - 2xy + 4xz + 2x^2 y - 4y^2 + 8yz`

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`27/15 x^3 yz^5 : 9/5 xz^2`

`= 9/5 x.x^2 yz^3 . z^2 : 9/5 xz^2`

`= x^2 y . z^3`

Phân tích thành nhân tử:

`3x^2 y -9xy^2 +12x^2 y^2`

`= 3xy (x - 3y + 4xy)`

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`x^3 - 6x^2 y + 12xy^2 - 8y^3`

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

`= (x - 2y)^3`