1000/z+6z-2z=410

                                                               1000/z+4z=410

Умножаем на z,                                 1000+ 4z^2=410z

                                                               4z^2-410z+1000=0

Делим на 2,                                         2z^2-205z+500=0

Решаем квадратное ур. Находим  D=(-205)^2-4*2*500

                                                                D=42025-4000=38025.

Находим два корня квадр. ур.   1)  z=(-(-205)+кв. корень из 38025)/2*2                                                                    z=(205+195)/4

                                                                z=400/4=100

                                                          2)  z=(205-195)/4

                                                                z=2,5