Question

What is an explicit formula for the geometric sequence -64,16,-4,1,... where the first term should be f(1).

Answer 1

`a_(n) = -64(-(1)/(4))^(n-1)`

it seems like the first term is -64, so lets write the formula accordingly:

a_n = a1(r)^(n-1)

where 'n' is the number of terms

a1 is the first term of the sequence

'r' is the ratio

the ratio is
`-(1)/(4)` because -64 *
`-(1)/(4)` = 16 and so on...

the explicit formula is :

`a_(n)` =
`-64(-(1)/(4) )^(n-1)`