Предмет: Алгебра, автор: Bajranataakasa

найдите сумму первых тридцати чисел арифметической прогрессии заданной формулой an=4n+9

Ответы

Автор ответа: fenix6810

0

Ответ:

2130

Объяснение:

s=(2a1+d(n-1))*n/2

a1=4+9=13

a2=8+9=17

d=a2-a1=4

s=(26+4*29)*30/2=142*15=2130

Предыдущий вопрос

Следующий вопрос

Похожие вопросы

Предмет: Технология, автор: HlebushekGrigoriy

Срочно!!!!
помогите " Лабороторная работа номер 5" ( начиная со 2 пункта)
дам 10 балов

1 год назад

Предмет: Окружающий мир, автор: окси126

самое близкое к земле небесное тело. а)плутон,б)солнце,в)полярная звезда,г)луна

1 год назад

Предмет: Английский язык, автор: kaysom

Помогите!!! Пожалуйста!!

1 год назад

Предмет: Английский язык, автор: uia67

Нужно составить диалог по английскому
пример:

7 лет назад

Предмет: Английский язык, автор: MalikZn

Choose the correct options.
1 I listened / was listening to the radio when I heard / was hearing this fantastic song.
2 When the teacher said / was saying ‘Stop!’, I still tried / was still trying to finish the last question.
3 I feel really silly! While I danced / was dancing, I fell / was falling and broke / was breaking my elbow.
4 Tim played / was playing a computer game when his mum called / was calling him for lunch.
5 I looked / was looking for a file on my memory stick when I noticed / was noticing there was a virus.
6 Ron found / was finding a really interesting website about dance music while he surfed / was surfing the internet.
7 My mum had / was having breakfast near the computer when she spilled / was spilling her cup of coffee on the keyboard.
8 When you saw / were seeing me yesterday, I didn’t go / wasn’t going to school, I went / was going to the doctor’s – I felt terrible.
9 How many pictures did you take / were you taking while you travelled / were travelling around Ireland?
10 Why did you chat / were you chatting to Philip while I tried / was trying to tell you something really important?

7 лет назад