Question

rút gọn (x + 1)^2 - (x - 1) ^2 - 3(x + 1 ) x (x - 1 )

 

Answer 1

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

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

`=2x.2+3x^2-3`

`=3x^2+4x-3`

Answer 2

Lời giải:

$(x+1)^2-(x-1)^2-3(x+1)x(x-1)$

$=(x+1-x+1)(x+1+x-1)-3x(x^2-1)$

$=4x-3x(x^2-1)=x[4-3(x^2-1)]=x(7-3x^2)$

 

Answer 3

Ta có: \(\left(x+1\right)^2-\left(x-1\right)^2-3\left(x+1\right)\left(x-1\right)\)

\(=x^2+2x+1-x^2+2x-1-3x^2+3\)

\(=-3x^2+4x+3\)