I have to pay my friend $1 increased by 50% each day for 20 days. How much do I have to pay him at the end of the 20 days.

So for this, you'll be using an exponential equation, which is y=ab^x (a = initial value, b = growth/decay).

Since you start off paying your friend $1, that will be your initial value. And since this is a 50% increase, you are to add 1 and 0.5 together (50% in decimal form), which is 1.5. That will be your b variable. And since # of days is the independent variable, that will be your x variable.

Using the previous info, this is our equation: y = 1 (1.5) ^20. From here we can solve for the total cost (y).

Firstly, solve 1.5^20: y = 1 (3325.26)

Next, multiply everything on the right side of the equation, and your answer will be (rounded to the hundreths) : y = 3325.26

In context, at the end of the 20 days, you have to pay your friend $3325.26.