(a^4+a^2+1)/a^2
=a^2+1+1/a^2
因为a+1/a=5
两边平方a^2+2+1/a^2=25
所以a^2+1+1/a^2=24
(a^4+a^2+1)/a^2=a^2+1/a^2+1=(a+1/a)^2-2+1=(a+1/a)^2-1=5^2-1=24
如果你问的是(a^4+a^2+1)/a^2
a+1/a=5,a^2+2+1/a^2=25
原式=a^2+1+1/a^2=24
a^2/[a^4+a^2+1]=?
[a+1/a]^2=a^2+1/a^2+2=25
a^2+1/a^2=23
[a^4+a^2+1]/a^2=a^2+1/a^2+1=23+1=24
(a^4+a^2+1)/a^2
=a^2+1+(1/a^2)
=(a+1/a)^2-1
=25-1
=24