Me! i have no clue what this even is and the whole lesson is full of them

ANSWER



EXPLANATION

The given series is



The k, stands for the nth term of the series.

The 3 at the top is the lasts term in the series.

We can write this in expanded form as



This will give us,



We can see that the subsequent terms are arrived at, by multiplying the previous terms by a constant number which is 8.

This constant number is called the common ratio, denoted by .

Thus


The first term of the series is


This simplifies to


The correct answer is C

The answer would be 10.