Question

another GP problem @ganeshie8

Answer 1

\[1+3^{2}+3^{4}+...+ 3^{2n}\]

Answer 2

how many terms are there in the series ?

Answer 3

it just asks you to add up to \[3^{2n}\]

Answer 4

lets count the number of terms again

Answer 5

Notice the exponents :

0, 2, 4, ... , 2n

Answer 6

how many terms are they ?

Answer 7

2n+1

Answer 8

@ganeshie8

Answer 9

nope

Answer 10

0, 2, 4, ... , 2n

if i divide each term by 2, the number of terms wont change, right ?

Answer 11

so lets divide by 2, you get :

0, 1, 2, ... , n

Answer 12

how many terms are they ?

Answer 13

n+1

Answer 14

yes

Answer 15

and r = 3^2 as you said earlier

Answer 16

use the partial sum formula :

\[\rm S_k = a_1 \dfrac{r^k-1}{r-1}\]

Answer 17

r = 3^2

k = n+1

Answer 18

ok i got it thanks!!!

Answer 19

ive got one more sorry