Выяснить что представляют собой множества aub anb a\b если: 5. a={2, 6, 8, 10, -10}, b={4, 5, 10, 11, -12};

aub={-12,-10,2,4,5,6,8,10,11}

anb={10}

a\b={2,6,8,-10}

1  yesterday i had  breakfast at the canteen.  2  last summer we went to the black sea.  3  he didn't call  me last week.  4  why did this girl come to  our office yesterday?   5  when did  you buy tickets last time?   6  last june the boys played  football every morning.  7  on sunday my parents  were at the theatre.  8  i didn't take part at the conference last month.  9  he lived in kiev in his childhood.  10  where did  he send his message?   2 трансформируйте предложения в past simplе  1  he often played chess.  2  our classes began at 9 a. m.  3  she  was always busy.  4  what did you do in the evening?   5  my sister didn’t study at school, she worked at the hospital. 6  my friend prefered tea to coffee.  7  i found many stories in this magazine.  8  he was in my room,  wasn't he?   9  why did you always ask so many questions?   10  jasmine seldom visited her grandparents.  3 образуйте отрицательную форму предложений  1  in summer she didn't get up early.  2  mr. white  didn't write a lot of letters yesterday.  3  on friday they weren't at the station.  4  we didn't  enjoy our time in rome.  5  they didn't  watch a football match last weekend.  6  the girl didn't open a box at once.  7  i didn't leave my keys on the table.  8  the engineer didn't go on business trip on monday.  9  my friend didn't want to move to another flat.  10  i didn't find a surprise in the present-box.  4 поставьте вопросы к предложениям.  1  he learned english at school. (where? what language? why? or …? )  where did he learn english? what language did he learn? why did he learn english? did he learn english or french? 2  the train was five hours late. (what? why? )  what was 5 hours late? why was the train five hours late? 3  i was going to stay at my aunt’s in the crimea. (where? who? or …? ) where was i going to stay in the crimea? who was going to stay at the aunt's in the crimea? was i going to stay at my aunt's or in the hotel in the crimea?   4  they stayed in moscow only for two days. (why? where? how long? ) why did they stay in m only for 2 days? where did they stay? how long did they stay in m?   5  i bought a very beautiful dress in this shop last weekend. (where? what? when? ) where did i buy a very beautiful dress last weekend? what did i buy in this shop last weekend? when did i buy this beautiful dress in the shop? 6  they traveled to cyprus by sea. (how? where? or …? ) how did they travel to c? where did they travel to? did they travel to c or ibiza?   7  i didn’t find your telephone number. (what? why? )  what didn't i find? why didn't i find your telephone number? 8  in his childhood he was always a leader among his friends. (what? when? who? )  what was he in his childhood? when was he a leader among his friends? who was always a leader among his friends in his childhood? 9  he caught a cold last month. (what? when? why? ) what did he catch? when did he catch a cold? why did he catch a cold?   10  we did our lessons together. (what? how? ) what did we do together? how did we do our lessons?

Среднее арифметическое всех чисел равно 50. Во второй группе среднее тоже 50. Это значит, что среднее арифметическое совокупности чисел первой и третьей групп также 50. Пусть в третьей группе n чисел, а их среднее арифметическое равно целому числу m. Получаем равенство

21*29=mn/n+29=50

откуда  n(m-50)=29^2

Число n является натуральным делителем числа 29^2. Возможно три варианта:

1) n = 1 n = 29 n = 29^2

Случай n = 29 невозможен, так как по условию в первой и третьей группах чисел не поровну. Случай n = 29^2 невозможен, так как  Следовательно,  n = 1

ответ: 1.