A ∪ B ∪ C, нужно собрать все уникальные элементы из множеств A, B и C в одно множество.{1, 2, 7, 8, 13, 20, 23, 26}{5, 7, 8, 9, 13, 20}{1, 7, 13, 17, 21, 22, 26, 29}{1, 2, 7, 8, 13, 20, 23, 26}5, 9. Множество становится: {1, 2, 5, 7, 8, 9, 13, 20, 23, 26}17, 21, 22, 29. Множество становится: {1, 2, 5, 7, 8, 9, 13, 17, 20, 21, 22, 23, 26, 29}Ответ: {1, 2, 5, 7, 8, 9, 13, 17, 20, 21, 22, 23, 26, 29}