已知x+1/x=3,求(xx)/(xxxx+xx+1)的值
问题描述：
已知x+1/x=3,求(xx)/(xxxx+xx+1)的值
答
(xx)/(xxxx+xx+1)
=x^2/(x^4+x^2+1)
=1/x^2+1+x^2
=x^2+1/x^2+2-1
=(x+1/x)^2-1
=3^2-1
=8