Question

В1=3, q=2 В5=? S5=?

Answer 1

Я  думаю, что прогрессия геометрическая.
b₁ =3,  q = 2,  b₅= ? S₅ = ?
решение:
b₅ = b₁*q⁴ = 3 * 2⁴ = 3 * 16 = 48
S₅ = b₁(q⁵ -1)/(q -1) = 3(32-1)/2 = 93/2 = 46,5

Answer 2

To find В5, we can use the formula for the nth term of a geometric sequence:

Bn = B1 * q^(n-1)

where Bn is the nth term, B1 is the first term, q is the common ratio, and n is the term number.

Plugging in B1 = 3, q = 2, and n = 5, we get:

B5 = 3 * 2^(5-1) = 3 * 2^4 = 3 * 16 = 48

So В5 = 48.

To find S5, we can use the formula for the sum of the first n terms of a geometric sequence:

Sn = (B1 * (1 - q^n)) / (1 - q)

Plugging in B1 = 3, q = 2, and n = 5, we get:

S5 = (3 * (1 - 2^5)) / (1 - 2) = (3 * (-31)) / (-1) = 93

So S5 = 93.