nhìn sao ra cách phân tích thành nhân tử hay quá vậy
$\frac{n^7+2n^2+n+2}{n^8+n^2+2n+2}=\frac{n^7-n+2(n^2+n+1)}{n^8-n^2+2(n^2+n+1)}=\frac{n(n^6-1)+2(n^2+n+1)}{n^2(n^6-1)+2(n^2+n+1)}=\frac{n(n-1)(n^2+n+1)(n^3+1)+2(n^2+n+1)}{n^2(n-1)(n^2+n+1)(n^3+1)+2(n^2+n+1)}=\frac{(n^2+n+1)(n^5-n^4+n^2-n+2)}{(n^2+n+1)(n^6-n^5+n^3-n^2+2)}$.