Question

A geometric series has a common ratio of -2 and the first term of 3. Find the sum of the first ten terms of the series.​

Answer 1

Answer:

-1023

Step-by-step explanation:

We have first term, a = 3, common ratio, r = -2 and number of terns, n = 10. Here, |r| = 2 > 1.

Sum of first n terms of a GP when |r| > 1

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

= $\frac{3((-2)^{10}-1) }{(-2)-1}$= $\frac{3(1023)}{-3}$ = -1023