x+1/x=3两边平方得x²+2+1/x²=9x²+1/x²=7x²/(x^4+x^2+1)=1/(x²+1+1/x²)=1/[(x²+1/x²)+1]=1/(7+1)=1/8
设X^2/(X^4+X^2+1)=A1/A=x^2+1+1/x^2 =(x+1/x)^2-1 =3^2-1 =8所以X^2/(X^4+X^2+1)=1/8
=1/8
