A population increases at a rate of 5% per year.

In 2000, it is = 10,000

What would was it in the year 1970?

I think I would use

d(1970) = 10,000 - (0.05)^30 (10,000)

I know that d(n) = (1.05)^n d(n-1) so if I needed to figure out the value in the year 2001 I would have

d(n) = 1.05^1 (10,000)

BUt going backwards I am not sure.