The exponential function that models the number of trees after t years is given by:
[tex]A(t) = 800\left(\frac{3}{4}\right)^t[/tex]
Hence, after 2 years, 450 trees will be remaining, as the graph at the end of this answer shows.
What is an exponential function?
A decaying exponential function is modeled by:
[tex]A(t) = A(0)(1 - r)^t[/tex]
In which:
- A(0) is the initial value.
- r is the decay rate, as a decimal.
In this problem:
- The forest has 800 pine trees, hence A(0) = 800.
- Each year, a disease is introduced that kills a fourth of the pine trees in the forest every year, hence [tex]r = \frac{1}{4}[/tex].
Then, the equation is:
[tex]A(t) = A(0)(1 - r)^t[/tex]
[tex]A(t) = 800(1 - \frac{1}{4})^t[/tex]
[tex]A(t) = 800\left(\frac{3}{4}\right)^t[/tex]
After 2 years:
[tex]A(2) = 800\left(\frac{3}{4}\right)^2 = 450[/tex]
450 trees will be remaining.
You can learn more about exponential functions at https://brainly.com/question/25537936
