Answer:
f(x) = 500(2)^x
Explanation:
if you go through each equation and substitute zero for 'x' you can determine which one will equal 500:
results of 1st option: 100 x 1 = 100
results of 2nd option: 100 x 0 = 0
results of 3rd option: 500 x 1 = 500
results of 4th option: 500 x 0 = 0
* remember that anything raised to the power of zero equals 1