При каких значениях переменных имеет смысл выражения 1)2х+5 2)7/5у-15 (можете объяснить и показать? )

Пошаговое объяснение:

А) при любых х

Б) у не равен 0

                                  Стеллерова или морская корова!The black book of extinct animals and describes another species, discovered during the expedition of Vitus Bering in 1741. His ship called the "St. Peter" was wrecked near the coast of the island, later named after its discoverer. The team was forced to stay here for the winter and to eat unusual animals called cows due to the fact that they were eating sea grass. These creatures were huge and slow. Their weight often reaches ten tons. The meat of the sea cow was very tasty and useful. Hunting on these harmless giants had not been difficult, as the animals calmly eating algae close to the coast, were not able to escape in the depth and wasn't afraid of the man. In the end, after the expedition to the Islands of profit brutal hunters who killed all the population of the sea cows for some three decades

1. х -1 часть в граммах

а) 3х=60, х=20

20*2=40 грамм яблок, 20 грамм апельсиноов

б)2х=50 х=25

25*3=75 грамм бананов, 50 грамм яблок, 25 грамм апепельсинов, 

вес салата=150грамм

в)х=100

100*3=300 грамм бананов, 200 грамм яблок, 100 грамм апельсинов

вес салата = 600 грамм

2. обозначи 1 число - а, 2 - а+1, 3- а+2, составляем уравнение:

а+а+1+а+2=48, 3а=45, а=15

1 число - 15, 2 - 16, 3- 17

 

3. 9 чисел. Доказать можно используя дерево вариартов.

   7         7          7

   |           |          |

   2- 2      7- 2     8- 2

   |            |          |

    8        8          8

4. делаешь как 3 задание. потом из всех ветвей выбираешь только те, где число четно