1. ## Sequences

a normal geometric sequence is:
un=u1*(r^n-1)

but a compound interest geometric sequence is:
u(n+1)=u1*(r^n)

how do i know when to use which?

2. Hello juliak
Originally Posted by juliak
a normal geometric sequence is:
un=u1*(r^n-1)

but a compound interest geometric sequence is:
u(n+1)=u1*(r^n)

how do i know when to use which?
These define the same sequence. The second is simply the first with $n$ replaced by $(n+1)$.