Question

What is the sum of the geometric sequence 8, -16, 32 . if there are 15 terms? (1 point)
What is the sum of the geometric sequence 4, 12, 36 . if there are 9 terms? (1 point)
What is the sum of a 6-term geometric sequence if the first term is 11, the last term is -11,264 and the common ratio is -4? (1 point)
What is the sum of an 8-term geometric sequence if the first term is 10 and the last term is
781,250? (1 point)?

Answer 1

well you need to know the 1st term a = 8

the common ratio r what you are multiplying by

and n the number of terms n = 15

then substitute into

\[S_{n} = \frac{a(1 - r^n)}{1 - r}\]

and then evaluate