题目应该是：x/(x^2-x-1)=7,求：x^2/(x^4+x^2+1)=?
由题知,x≠0,所以已知两边同时取倒数,得
(x^2-x-1)/x=1/7
x-1-/x=1/7
x-1/x=8/7
上式两边同时平方,得
x^2+1/x^2-2=64/49
x^2+1/x^2=162/49
先算
(x^4+x^2+1)/x^2
=x^2+1/x^2+1
=162/49+1
=211/49
所以
x^2/(x^4+x^2+1)=49/211