Question

Sigma notation

Answer 1

@satellite73 Help please!

Answer 2

@Miracrown Help please!

Answer 3

Replace n by 1 to 7
Then add them up.. U get the answer :)

Answer 4

when n=1, the answer is 2. when n=2, the answer is -4. then 3 is 8. then 4 is -16. Find a pattern yet?

Answer 5

2, -4, 8, -16, 32, -64, 128...

Answer 6

\[
\sum_{k=0}^nar^k=\frac{a(r^{n+1})}{r-1}
\]

Answer 7

Holy damn there are so many different variables I can't even.

Answer 8

\[\sum_{k=0}^nar^k=\frac{a(r^{n+1})}{r-1}=a+ar+ar^2+ar^3+ar^4+\cdots+ar^n\]
a and r are constants.

Answer 9

when n=1,first term a=2
r=-2
\[s=a \frac{ r^n-1 }{ r-1 }\]
n=7
s=?