Question

What is the sum of the first eight terms of a geometric series whose first term is 3 and whose common ratio is ?
A.

B.

C.

D.

Answer 1

Answer:

See explanation

Step-by-step explanation:

The sum of the first n terms of a geometric sequence is given by:

$S_n= \frac{a(1 - {r}^{n} )}{1 - r}$

Where a=3 is the first term and n=8.

Unfortunately you missed out the common ratio r.

When the available information is substituted, we get:

$S_8= \frac{3(1 - {r}^{8} )}{1 - r}$

If we had known the value of r, we would have simplified further.