a^2+4a-1=0
a+4-1/a=0
a-1/a=-4
(1)a^2+1/a^2
=(a-1/a)^2+2
=16+2
=18
(2) (a+1/a)^2
=a^2+2+1/a^2
=18+2
=20
(3) a^4+1/a^4
=(a^2+1/a^2)^2-2
=18^2-2
=322
a^2+4a-1=0
a+4-1/a=0
a-1/a=-4
(1)a^2+1/a^2
=(a-1/a)^2+2
=16+2
=18
(2) (a+1/a)^2
=a^2+2+1/a^2
=18+2
=20
(3) a^4+1/a^4
=(a^2+1/a^2)^2-2
=18^2-2
=322