a+1/a=3 得a^2+2+1/a^2=9得a^2+1/a^2=7
而a^2/(a^4+a^2+1)分子分母除以a^2,则分子为1,
分母为a^2+1+1/a^2=7+1=8.
则a^2/(a^4+a^2+1)=1/8.
a+1/a=3
两边平方得
a^2+2+1/a^2=9
则a^2+1/a^2=7
(a^4+a^2+1)/a^2
=a^2+1+1/a^2
=7+1
=8
a+1/a=3
两边平方得
a^2+2+1/a^2=9
则a^2+1/a^2=7
(a^4+a^2+1)/a^2
=a^2+1+1/a^2
=7+1
=8