The resale value of a textbook decreases by 25% with each previous owner. A new textbook is sold for $85. What is the function represents the resale value of the textbook after x owners?
It is not linear. It is an exponential function.
If a new book worths $85, then used once book worths $63.75.
Used twice book worths $47.81
Used three times book worths $35.86
Now your equation (I computed this using Microsoft Excel)
x represents owner number. For example 5th owner of the book buys this book
Let new cost after each sale be
The first reduction is:
This is the same as:
This process repeats for each successive depreciation.