a: \(A=x^{8n}+x^{4n}+1\)
\(=x^{8n}+2x^{4n}+1-x^{4n}\)
\(=\left(x^{4n}+1\right)^2-\left(x^{2n}\right)^2\)
\(=\left(x^{4n}+x^{2n}+1\right)\left(x^{4n}-x^{2n}+1\right)\)
b: \(\dfrac{x^{4n}+x^{2n}+1}{x^{2n}+x^n+1}=\dfrac{x^{4n}+2x^{2n}+1-x^{2n}}{x^{2n}+x^n+1}\)
\(=\dfrac{\left(x^{2n}+1\right)^2-\left(x^n\right)^2}{x^{2n}+x^n+1}=x^{2n}+1-x^n\)
=>A chia hết cho B