\(2\left(x^2+x+1\right)^2-\left(2x+1\right)^2-\left(x^2+2x\right)^2\)
\(=2\left(x^4+2x^3+3x^2+2x+1\right)-4x^2-4x-1-x^4-4x^3-4x^2\)
\(=2x^4+4x^3+6x^2+4x+2-4x^2-4x-1-x^4-4x^3-4x^2\)
\(=x^4-2x^2+1\)
\(=\left(x^2-1\right)^2\)
\(=\left[\left(x-1\right)\left(x+1\right)\right]^2\)
\(=\left(x-1\right)^2\left(x+1\right)^2\)
Chúc bạn học tốt.