Question

The first term of a geometric sequence is 7, and the ratio (multiplier) is 3. what is the sum of the first 5 terms of the sequence? user: what is the 8th term of this geometric sequence? 6, 48, 384, 3072, . . .

Answer 1

Hello,

1)

`a_(1)=7`

`a_(2)=7*3`

`a_(3)=7*3^2`


`a_(n)=7*3^(n-1)`


`s=a_(1)+a_(2)+a_(3)+a_(4)+a_(5)=7*(1+3^1+3^2+3^3+3^4)`

`=7*(3^(5)-1)/(3-1)`

`=7*242/2=847`

2)

`b_(8)=6*8^(8-1)=12582912`