Андрей ********** sqrt(x) / (1+x) dx x= tg^2(t) dx = 2tg(t)/cos^2(t) dt tg(t) / (1+tg^2(t)) * 2tg(t) / cos^2(t) dt = 2tg^2(t) dt = 2(1/cos^2(t) -1) dt интегрируем 2tg(t) -2t = 2sqrt(x) - 2arctg(sqrt(x))