Question

Find the sum of a finite geometric sequence from n = 1 to n = 7, using the expression −4(6)n − 1.

111,325

526

782

-223,948

Answer 1

plug 1 and 7 into the equation as n and solve i believe.

Answer 2

thankyou finally lol ive been trying to find someone to tell me how to solve these

Answer 3

I think thats how you do it XD

Answer 4

hmm i got 186,624

Answer 5

@Abhisar @dan815 @rose21 @texaschic101 any one know this?

Answer 6

@phi @ganeshie8 @kirbykirby any one know this?

Answer 7

\[ f(n)= −4\cdot 6^{n − 1} \]
the sum of a geometric series from n= 1 to 7 will be the same as
\[\sum_{i=0}^{6}4\cdot 6^i\]

Answer 8

there is a formula for that sum. see
https://en.wikipedia.org/wiki/Geometric_series#Formula