Question

Zack bought a baseball card for $20. One year later, he looked up the value of the card and saw that it had gone up by 5%. Assuming the same growth continues, you can use a function to approximate the value of the baseball card x years after Zack purchased it.
Write an equation for the function. If it is linear, write it in the form f(x)=mx+b. If it is exponential, write it in the form f(x)=a(b)x.

Answer 1

The value grows by 5% per year, so it's exponential. The function is

f(x) = 20(1.05)^x

where x is years after purchase.