\(=\left[\left(x-1\right)-\left(x+1\right)\right]\left[\left(x-1\right)^2+\left(x-1\right)\left(x+1\right)+\left(x+1\right)^2\right]\\ =\left(x-1-x-1\right)\left(x^2-2x+1+x^2-1+x^2+2x+1\right)\\ =-2\left(3x^2+1\right)\\ =-6x^2-2\)
(x−1)3−(x+1)3(x-1)3-(x+1)3
Bài làm
=(x−1−x−1)[(x−1)2−(x−1)(x+1)+(x+1)2]=(x-1-x-1)[(x-1)2-(x-1)(x+1)+(x+1)2]
=−2(x2−2x+1−x2+1+x2+2x+1)=-2(x2-2x+1-x2+1+x2+2x+1)
=−2(x2+3)=-2(x2+3)
=−2x2−6
Xin 1 tick
`(x-1)^3 - (x+1)^3 `
`=[(x-1)-(x+1)][(x-1)^2 + (x-1)(x+1) +(x+1)^2 ]`
`=(x-1-x-1)[(x^2 - 2x +1) + x^2 -1 +(x^2 + 2x+1)]`
`=-2(x^2 -2x+1+x^2 -1 + x^2 + 2x+1)`
`=-2(3x^2 +1)`