a \(=x^4+4x^2+4-4x^2\)
\(=\left(x^2+2\right)^2-4x^2\)
\(=\left(x^2+2x+2\right)\left(x^2-2x+2\right)\)
b: \(=4x^8+4x^4+1-4x^4\)
\(=\left(2x^4+1\right)^2-4x^4\)
\(=\left(2x^4+1+2x^2\right)\left(2x^4+1-2x^2\right)\)
c: \(=x^4+16x^2+64-16x^2\)
\(=\left(x^2+8-4x\right)\left(x^2+8+4x\right)\)