Question

Find a formula for an
a) a1=2, r=5

Can someone show me how to do this?! Thanks!!

Answer 1

a)

The geometric series  of n terms is ar⁰ + ar + ar² + ar³ + .................+ ar^(n-2) + ar^(n-1)

Where a = first term and r = common ratio

Given that

The first term a1 = a = 2 , common ratio = r and nthterm = an = ar^(n-1)

Substitute a = 2 and r = 5 in the nth term an

an = 2(5)^(n-1) .