Tìm x 1, ( x + 2 ) ² – x ( x + 1 ) 2, ( 2 – 2x ) ² – 4( x ² + 1 ) = 5 3, ( x – 3 ) ( x + 3 ) – x( x + 2 )

Đáp án:

1. `(x + 2)^2 – x(x + 1) = 6`

`<=> x^2 + 2x + 1 – x^2 – x = 6`

`<=> x + 1 = 6`

`<=> x = 5`

2 . `(2 – 2x)^2 – 4(x^2 + 1) = 5`

`<=> 4 – 8x + 4x^2 – 4x^2 – 4 = 5`

`<=> -8x = 5`

`<=>x = -5/8` 

3 .`(x – 3)(x + 3) – x(x + 2) = 8`

`<=> x^2 – 9 – x^2 – 2x = 8`

`<=> -9 – 2x = 8`

`<=> 2x = -9 – 8`

`<=> 2x = -17`

`<=> x = -17/2`

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