x+1/x=3 x(x+1/x)^2=9x^2+1/x^2=7x+1/x=3x^2-3x+1=0(等式两边同乘以x)由球根公式得到x=(3±√5)/2x^2/(x^4+x^3+1)=1/(x^2+x+1/x^2) (分子分母同时除以x^2)=1/(x+7)=(17±√5)/142
x+(1/x)=3[x+(1/x)]²=9x²+2+(1/x²)=(x²+(1/x²)=7则:[x²]/[x^4+x²+1]=1/[(x²)+(1/x²)+1]=1/8