Question

What is the sum of the geometric sequence 1, –4, 16, … if there are 7 terms

Answer 1

The sum of a geometric sequence is:

\(\Large \color{Black}{\Rightarrow a \times {1 - r^n \over 1 - r} }\)

n is the number of terms.
r is the common ratio.
a is the first term.

Answer 2

Common ratio here is -4.

Answer 3

3277 thanks!!(:

Answer 4

Hehe you're welcome :D