A, or f(x) = 8,000(1/4)^x
8,000 is our starting number since number of half lives is our x, and at x = 0, remaining amount of substance is equal to 8,000. As we can see on the graph, the number decreases by a quarter of its original value every time. Since the number is not getting bigger, we use a fraction instead of a whole number. Finally, the exponent makes sure that it’s a quarter of the product from before.
Hope this helps!
