Denise G. answered • 06/20/19

Algebra, College Algebra, Prealgebra, Precalculus, GED, ASVAB Tutor

This looks like a geometric sequence. The formula for this would be

a_{n}=a_{1}(r)^{n-1}

a_{1} is the initial value = 2500

r is the common ratio = 2 because it is doubling every year

n the number of years = 9

Plugging these into the equation

a_{9}=2500(2)^{(9-1) } = **640,000 is the population of the city after 9 years**

I used a table to check my work as well. (Not good if you were doing too many years but 9 isn't bad)