Question

Graph the six terms of a finite series where a1 = 5 and r = 1.25. I looked through my lessons and honestly do not get how to do this. I know I am supposed to use the equation Sn=(a1-a1r^n)/(1-r) Mathematics

Answer 1

The sum of a geometric sequence is:

s(n)=a(1-r^n)/(1-r)

The sequence rule for a geometric sequence is:

a(n)=ar^(n-1)

Not sure what they mean by "graph the six terms"

The sum of the first six terms is in this case:

s(6)=5(1-1.25^6)/(1-1.25)

s(6)=56.2939453125

The first six terms in sequence is in this case:

a(n)=5(1.25)^(n-1) so

5, 6.25, 7.8125, 9.765625, 12.20703125, 15.2587890625