x^2/(x^4+x^2+1)=x^2/[(x^2+1)^2-x^2]=x^2/(x^2+1-x)(x^2+1+x)=1/7(x/x^2+x+1)
由x/(x^2-x+1)=1/7得:x^2+x+1=9x
所以,1/7(x/x^2+x+1)=1/63
x^2/(x^4+x^2+1)=x^2/[(x^2+1)^2-x^2]=x^2/(x^2+1-x)(x^2+1+x)=1/7(x/x^2+x+1)
由x/(x^2-x+1)=1/7得:x^2+x+1=9x
所以,1/7(x/x^2+x+1)=1/63