`(9x^2 -4). (x+1) = (3x+2). (x^2 -1)`

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

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

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

`<=> 3x+2=0` hoặc `x+1=0` hoặc `2x -3=0`

`<=> x =-2/3` hoặc `x=-1` hoặc `x =3/2`

Vậy `x =-2/3 ; x = 3/2 ; x=-1`

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`(x^2 -4). (4x-1) = (x-2) . (16x^2 -1)`

`<=> (x-2). (x+2) . (4x-1) = (x-2). (4x -1). (4x+1)`

`<=>(x-2). (x+2). (4x-1) - (x-2). (4x-1). (4x+1)=0`

`<=> (x-2). (4x-1). (x+2 - 4x-1)=0`

`<=> (x-2). (4x-1) . ( -3x +1)=0`

`<=> x-2=0` hoặc `4x -1=0` hoặc  `-3x +1=0`

`<=> x=2` hoặc `x =1/4` hoặc `x = 1/3`

Vậy `x =2; x = 1/4 ; x=1/3`

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

`<=> x^2 -2x +1 +x^2 -1 = x^2 +3x -x -3`

`<=> x^2 -4x +3=0`

`<=> x^2 -x -3x +3=0`

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

`<=> (x-1). (x-3)=0`

`<=> x-1=0` hoặc `x-3=0`

`<=> x=1` hoặc `x=3`

Vậy `x=1; x=3`.

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`(2x-3)^2 + 4x^2 -9 = (2x-3). (3x+5)`

`<=> 4x^2 - 12x +9 +4x^2 -9 = 6x^2 + 10x - 9x - 15`

`<=> 2x^2 -13x +15=0`

`<=> 2. (x-5). (x-3/2)=0`

`<=> x-5=0` hoặc `x-3/2=0`

`<=> x=5` hoặc `x=3/2`

Vậy `x= 5 ; x= 3/2`.

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`(x-3)^2 -9 +x^2 = (x-3). (x+1)`

`<=> x^2 -6x +9 -9 +x^2 = x^2 +x -3x -3`

`<=> x^2 -4x +3=0`

`<=>x^2 -3x -x +3=0`

`<=> x(x-3) -(x-3)=0`

`<=> (x-3). (x-1)=0`

`<=> x-3=0` hoặc `x-1=0`

`<=> x=3` hoặc `x=1`

Vậy `x=3; x=1`.