Упростите выражение:
(3/9-у^2+ 1/у-3):у/у^2-6у+9

1)  3/(9-y^2)  - 1/(3-y) = (3-(3+y) / (9-y^2) = -y/(9-y^2) = y/(y^2-9)2)  y/(y^2-9)  * (y-3)^2/y =  (y-3)^2/(y-3)(y+3)=(y-3)/(y+3)