I use ferrari method to find roots. Then i got next equation 1/((x-a)*(x-b)*(x-c)*(x-d)), where a,b,c,d -roots of equation. How to calculate such an integral??? If someone can answer here or kilik94@yandex.ru, i would be very grateful!

i'm not exactly sure of the solution but i think you could use rezidue theorem and solve the complex integral