Признак делимости на 19 для двухзначного числа: ху делится на 19, когда х+2у делится на 19. Например: 19 => 1+2*9=1+18=19 => 19/19=1
Нам нужно двухзначное число больше 40, которое, при делении на 19, дает остаток 1.
Пусть ху - искомое число
{ 10x+y>40
{x+2y≥19 => x≥19-2y
10(19-2y)+y>40
190-20y+y>40
19y>150
y>7 17/19 => y>7
x≥19-2y≥19-14≥5
1. Имеем: десятки искомого числа ≥5, единицы >7; если предположить, что х=5, у=7, то 5+2*7=19, значит 57 кратно 19: 57/19=3.
Если xy>57, то => 58/19=3(ост.1)
Далее, находим еще двухзначные числа, соответствующие условию:
2. 19*4=76 => 76+1=77 => 77/19=4(ост.1)
3. 19*5=95 => 95+1=96 => 96/19=5(ост.1)
ответ: Существуют 3 числа, делящиеся на 19 с остатком 1: 58; 77; 96
Today, I am at home. It is Saturday morning and it is very cold. Last month, my family and I were on
holiday in Canada. The weather is fantastic! It is really hot and sunny. We were happy then
The last vacation was great, but now I am
happy to be back. It is nice to be with all my friends.
Twenty years ago, there were no cars on the street where I lived.There was only one bakery in the whole town. There was no Internet at that time, so we sent letters to communicate with friends and family who lived far away. I didn't like to go to school far away because, the bus stop was from my house. Now, the street in front of my house.
There are many cars and buses. There are also many shops and there is big a department store right next to my house!
Yesterday, there was police blockade on the road because there was a robbery. I was
very scared and my parents worried because it happened in front of my house. This
morning, I heard that the robber got caught and I am glad that finally our place is safe!
на фото..............