Question

the sum of the first n terms of a sequence is 20 - 10 / 2 ^ n - 1 find the sum of the first five terms​

Answer 1

Answer:

$S_5=\dfrac{170}{9}$

Step-by-step explanation:

Given that,

The sum of first n term of a sequence is$S_n=20-\dfrac{10}{2n-1}$

We need to find the sum of the first 5 terms.

Put n = 5,

$S_5=20-\dfrac{10}{2(5)-1}\\\\=20-\dfrac{10}{10-1}\\\\=20-\dfrac{10}{9}\\\\=\dfrac{170}{9}$

So, the sum of first 5 terms is equal to $\dfrac{170}{9}$.