Question

已知a2-5a+1=0,求a4+a2+1/a2=

Answer 1

(1+5)×(10-6)=24

(10-1-5)×6=24

(a+b)2=22

a2+b2+2ab=4

a2+b2=4-2ab=4+2=6

所以b/a+a/b

=(a2+b2)/ab

=6/(-1)

=-6