Question

The 5th term of the expontential sequence is 4375 and 2nd term is 35,
(a) Find the 6th term
(b) Sum of the five term

Answer 1

since T5 = 3 terms after T3, you have
r^3 = 4375/35 = 125 = 5^3

So, use that to find a, and then recall that
S5 = a (r^5-1)/(r-1)

Answer 2

Good