x除以（x平方减x加1）=7两边取倒数得(x^2-1)/x=1/7即x-1/x=1/7两边同时平方得x^2+(1/x^2)-2=1/49即x^2+(1/x^2)=99/49令y=x平方除以（x的4次方+x的平方加1）所以1/y=x^2+1+1/x^2=1+99/49=148/49即原式等于49/198...