GP question (1 Viewer)

[flon]

Which term of the series

8 - 4 + 2 - ... is equal to 1/128?

Thanks in advance.

 

[GUSSSSSSSSSSSSS]

Which term of the series

8 - 4 + 2 - ... is equal to 1/128?

Thanks in advance.

its a GP
so find wat the common ratio is: in this case its: -1/2

then find an expression for the nth term: Tn = ar^(n-1)

Tn = 8.(-1^2)^(n-1)

and then solve for Tn = 1/128
(sorry i cbb to type it up)

naturally you will end up using logarithms

 

[Affinity]

Which term of the series

8 - 4 + 2 - ... is equal to 1/128?

Thanks in advance.

Series -> Never... (the partial sums are always bigger than 4).

if you are refering to the sequence 8, -4, 2, -1, 1/2, -1/4, 1/8, -1/16, 1/32, -1/64, 1/128

then it is the eleventh term