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27.05.2020 10:18

5 4. Задана геометрическая прогрессия (ъ). Найдите: 1) q, если b. 54; 2) q, если ъ, 3) q, если b, -13, b = 169; 4) q, если Ь, 18, b, - b 33, b, = 44; 0,4, bo = -0,08 E - 3 b6 =

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aliina000
13.08.2020 03:00
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?
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Ответ:
MatthewSan
13.02.2021 01:01
Обозначим длину l cм, ширину b см.
P = 2(l + b) = 40
2l + 2b = 40
2l = 40 - 2b = 2(20 - b)
l = 20 - b
S1 = l*b = (20 - b)*b = 20b - b^2

Изменим размеры по условию, получаем
длина = (l-3) см = 20 - b - 3 = 17 - b
ширина = (b + 6) см
Площадь нового прямоугольника
S2 = (l-3)* (b + 6) = (20 - b - 3)*(b + 6) = (17 - b)*(b + 6) = 17b - b^2  + 102 - 6b = 11b - b^2 + 102  
S2 = S1 + 3
  20b - b^2 + 3 = 11b - b^2 + 102
20b - b^2 - 11b + b^2 = 102- 3
9b = 99
b = 11 см
l = 20 - b = 20 - 11 = 9 см
S1 =  l*b = 11*9 = 99 см^2

Проверка:  l = 9-3=6 см
                   b = 11+6 = 17 см
                   S2 = 6*17=102 см^2
                   S2 - S1 = 102 - 99 = 3 см^2

ответ: площадь первоначального прямоугольника 99 см^2.

 

 
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