Упростите выражение

(25 / a^2 + 5a + 25 - 2a / 5 - a + a^3 + 25a^2 / a^3 - 125) * (a - 5 + 15a / a-5)

1) 25 / (a²+5a+25) + 2a / (a-5) + (a³+25a²) / (a-5) (a²+5a+25) =

= (25a-125+2a³+10a²+50a+a³+25a²) / (a-5) (a²+5a+25) =

= (3a³+35a²+75a-125) / (a-5) (a²+5a+25)

2) a-5 + 15a / (a-5) = (a²-10a+25+15a) / (a-5) = (a²+5a+25) / (a-5)

3) (3a³+35a²+75a-125) / (a-5) (a²+5a+25) * (a²+5a+25) / (a-5) = (3a³+35a²+75a-125) / (a-5) ²