A. Phân tích đa thức 1. x ³ + 2x ²y + xy ² - 4x 2. x ²-7xy + 10y ²

Đáp án:

`a,` `x^3 + 2x^2y + xy^2 - 4x`

`=(x^3+x^2y)+(x^2y+xy^2)−4x`

`=x^2.(x+y)+xy.(x+y)−4x`

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

`= (x + y).[x.(x + y)] - 4x`

`= x.(x +  y)^2 - 4x`

`=x.[(x+y)^2−2^2]`

`=x.(x+y+2).(x+y−2)`

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`b,` `x^2 - 7xy + 10y^2`

`= x^2 - 2xy - 5xy + 10y^2`

`= x.(x - 2y) - 5y.(x - 2y)`

`= (x - 2y).(x - 5y)`

$@dariana$