Question

1.What is the sum of the geometric sequence 8, –16, 32 … if there are 15 terms?
with work ? please

Answer 1

262136 is the answer ?

Answer 2

\[r=-2\] it looks like

Answer 3

thank you guys

Answer 4

No it's this
The first term is 8, and the second is -16
Thus, this is a sum of the form (8)(-2)^n
we have:
Summation of 8(-2)^n from n = 0 to n = 14
= 8 [Summation of (-2)^n from n = 0 to n = 14]
= 8 [((-2)^(15) - 1) / (-2 - 1)]
= 87384

Answer 5

so you have
\[8(1+(-2)+(-2)^2+(-2)^3+...+(-2)^{14}\]

Answer 6

okay

Answer 7

end up with
\[8\times \frac{(-2)^{15}-1}{-2-1}\] if a remember correctly

Answer 8

what jackie said

Answer 9

so the answer is 87384 ?

Answer 10

yes i believe so.

Answer 11

thank you

Answer 12

no problem