I think you solved it on your own because x is 82
Answer:
C) 65,535
Step-by-step explanation:
You can add up the 8 terms ...
3, 12, 48, 192, 768, 3072, 12288, 49152
to find their sum is 65535.
_____
<em>Estimating</em>
Knowing the last term (49152) allows you to make the correct choice, since the sum will be more than that and less than double that.
_____
<em>Using the formula</em>
You know the formula for the sum of a geometric sequence is ...
S = a1(r^n -1)/(r -1)
where a1 is the first term (3), r is the common ratio (4), and n is the number of terms (8).
Filling in the values, you find the sum is ...
S = 3(4^8 -1)/(4-1) = 4^8 -1 = 65535
