【x的（2n+3）次方+（8乘x的2n次方）】除以【x的（n+4）次方+(4乘x的（n+2）次方）+16乘x的n次方】
=(X^2n*x^3+8*x^2n)除以(x^n*x^4+4*x^n*x^2+16x^n)
=x^2n(x^3+8)除以x^n(x^4+4x^2+16)
=x^n(x^3+8)/(x^4+4x^2+16)
已是最简整式,无法继续化简