Thực hiện phép tính c. ( $x^{n}$ + $y^{n}$) . ( $x^{2n}$ - $x^{n}$ . $y^{n}$ + $y^{2n}$) . ( $x^{3n}$ - $y^{3n}$) ( n thuộc N) Tìm x: b. ( 2x-1).( 3-x) + ( x-2).( x+3) = ( 1-x).( x-2)

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

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

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

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

`= x^(6n) - y^(6n)`

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`(2x - 1)(3 - x) + (x - 2)(x + 3) = (1 - x)(x - 2)`

`<=> (2x - 1)(3 - x) + (x - 2)(x + 3) - (1 - x)(x - 2) = 0`

`<=> (2x - 1)(3 - x) + (x - 2)(2x + 2) = 0`

`<=> 5x - 7 = 0`

`<=> x = 7/5`

Vậy `x = 7/5`