(b-1/a)/(b^2+2/a^2 )

(b-1)/a /(b^2 + 2/a^2)

(b-1)/a * 1/(b^2 + 2/a^2) =

(b-1) / a(b^2 + 2/a^2) =
(b - 1) / (ab^2 + 2/a)