Question

What is the explicit formula for this geometric sequence? 5,10,20,40,80,160,...

Answer 1

an = 5·2^(n-1)

Explanation:

The explicit formula for a geometric sequence with first term a1 and common ratio r is ...

an = a1·r^(n-1)

Your sequence has a1=5 and r=2, so the explicit formula is ...

an = 5·2^(n-1)