\(\left(x^2-2\right)\left(x^2-2x+2\right)\left(x^2+2x+2\right)\left(x^2+2\right)\)
\(=\left[\left(x^2-2\right)\left(x^2+2\right)\right].\left\{\left[\left(x^2+2\right)-2x\right].\left[\left(x^2+2\right)+2x\right]\right\}\)
\(=\left(x^4-4\right).\left[\left(x^2+2\right)^2-4x^2\right]\)
\(=\left(x^4-4\right)\left(x^4+4x^2+4-4x^2\right)=\left(x^4-4\right)\left(x^4+4\right)\)
\(=x^8-16\)