x=（4-√7）/3x²=(16+7-8√7)/9=(32-8√7)/9-9/9所以x²=(8/3)x-1即x²+1=(8/3)x所以 x+1/x=8/3(x+1/x)²=64/9x²+1/x²+2=64/9所以 x2/(x4+x2+1)=1/(x²+1+1/x²)=1/(64/9-1)=1/(...