Question

(4x-5)(x+1)-4(x-1)(x+1)=7

Answer 1

`(4x-5)(x+1)-4(x-1)(x+1)=7`

`<=>4x^2+4x-5x-5-4x^2+4=7`

`<=>4x-5x=7+5-4`

`<=>-x=8<=>x=-8`

Vậy `S={-8}`

Answer 2

`(4x-5)(x+1)-4(x-1)(x+1)=7`

`<=>4x^2 -5x+4x-5-4(x^2-1)=7`

`<=>4x^2 -4x^2 -x-5+4=7`

`<=>-x-1=7`

`<=>-x=7+1`

`<=>-x=8`

`<=>x=-8`

Answer 3

Lời giải:

$(4x-5)(x+1)-(4x-4)(x+1)=7$

$\Leftrightarrow (x+1)[(4x-5)-(4x-4)]=7$

$\Leftrightarrow (x+1)(-1)=7$

$\Leftrightarrow x+1=-7$

$\Leftrightarrow x=-8$