Question

What is the explicit formula for the sequence: 8, -20, 50, -125?

Answer 1

`a_n=8*(-5/2)^n, n>=0`

Explanation:

It is not possible to be certain with a limited sample sequence but this appears to be a geometric series with
`color(white)("XXX")a_0=8`
and
`color(white)("XXX")a_i=a_(i-1)*(-5/2)`
which would give the equation in the "Answer" above.