a/a的平方-3a+1=2
1/(a-3+1/a)=2
a+1/a-3=1/2
a+1/a=7/2 平方
a^2+2+1/a^2=49/4
a^2+1/a^2=41/4
a的平方/a的四次方+a的平方+1
=1/(a^2+1+1/a^2)
=1/(41/4+1)
=1/(45/4)
=4/45