<h2>Answer</h2>
f(x) = 5(1.25)x + 4
<h2>Explanation</h2>To solve this, we are going to use the standard exponential equation:
where
is the initial amount
is the growth rate in decimal form
is the time (in months for our case)
Since the hours of classic music remain constant, we just need to add them at the end. We know form our problem that Sue initially has 5 hours of pop, so ; we also know that every month onward, the hours of pop music in her collection is 25% more than what she had the previous month, so
. Now let's replace the values in our function:
Now we can add the hours of classical music to complete our function:
