Explanation:
so, it starts (year 0 after 2000) with 350 foxes.
after 1 year the number had increased by 5%.
that means : 350×1.05
because 5% is represented by 0.05.
5% of 350 is 350×0.05 (= 17.5)
and to add 5% means that this is added to the original 100% (= 1).
100% + 5% = 105%
means
1 + 0.05 = 1.05
so, again, after the first year we have
350×1.05
foxes.
after the second year we have to multiply that by 1.05 again :
350×1.05×1.05
and so on.
so, what we are doing is multiplying the original number of foxes by powers of 1.05 (with the exponent being the number of years after 2000).
f(x) = 350 × (1.05)^x