Question

Дано арифметичну прогресію Bn знайдіть b1 якщо d=4 n =8 S=8​

Answer 1

Ответ:

- 13.

Пошаговое объяснение:

(bn) - арифметическая прогрессия

d = 4

S8 = 8

Найдём b1.

Решение:

Sn = (2b1 + d(n-1))•n/2

В нашем случае

S8 = (2b1 + 4•7)•8/2

8 = (2b1 + 28)•4

2b1 + 28 = 8:4

2b1 + 28 = 2

2b1 = 2 - 28

2b1 = - 26

b1 = - 13

Answer 2

Sure thing! To find $b_1$ in an arithmetic progression, you can use the formula for the sum of an arithmetic series:

$S_n = \frac{n}{2}[2a_1 + (n-1)d]$

Here, $S_n$ is the sum, $n$ is the number of terms, $a_1$ is the first term, and $d$ is the common difference.

You mentioned that $d = 4$, $n = 8$, and $S = 8$. We need to find $a_1$.

Let's plug in the values and solve for $a_1$:

$8 = \frac{8}{2}[2a_1 + (8-1) \times 4]$

Simplify the equation:

$1 = 2a_1 + 28$

Subtract 28 from both sides:

$-27 = 2a_1$

Divide by 2:

$a_1 = -\frac{27}{2}$

So, $b_1$ (since $b_1$ is the same as $a_1$ in an arithmetic progression) is $-\frac{27}{2}$.