Question

A11=20 ; a = 3 ; a1 - ? прогрессии​

Answer 1

Ответ:

Пошаговое объяснение:

a11=a1+10d,  20=a1+10*3,  a1=20-30,  a1=-10

Answer 2

To determine the arithmetic progression A1, we need to know the common difference (d) between consecutive terms. In an arithmetic progression, each term is obtained by adding the common difference to the previous term.

The formula for the nth term (An) of an arithmetic progression is given by:

An = A1 + (n - 1) * d

where: An = nth term A1 = first term n = term number d = common difference

In your question, you've provided the value of A11 (11th term) as 20, and the common difference (a) as 3.

Let's find the first term (A1) using the formula:

A11 = A1 + (11 - 1) * 3 20 = A1 + 10 * 3 20 = A1 + 30

Now, solve for A1:

A1 = 20 - 30 A1 = -10

So, the first term (A1) of the arithmetic progression is -10.