Question

What is the sum of a 6–term geometric series if the first term is 6 and the last term is 1,000,842?

188,851

157,962

138,073

117,648

Answer 1

do u know the formula for 'n' th term of geometric sequence?

Answer 2

Nope

Answer 3

its Tn=a*R^(n-1)
a is 1st term given as 6
R is common ratio
n=6 as number of terms is 6
so can u find R from this?

Answer 4

So I plug it in and get Tn=a*R^(6-1)?

Answer 5

the 6th term given to u =T6=1000842
now u have T6,n,a...find R from the formula

Answer 6

So it would be 138,073?

Answer 7

no R will be 11.077
then u put formula for sum of GP
which is a(R^n-1)/(R-1)

Answer 8

Nooo, I knew the second formula, I was saying the final answer is 138,073?

Answer 9

i think the options or question is incorrect,because if last term is 1000842,how come the sum is less than it?

Answer 10

did u put an extra 0?

Answer 11

Nope, the question is correct,I just checked again.

Answer 12

no its 100842 only,because then R=7

Answer 13

and your sum is 117648

Answer 14

THANK YOU!