Order in ascending order 1.2, 3.1, 2.1

b. f(x) = –√x + 3this is the correct answer

answer:

at time x=0 we have 1000, at time x=1 we have 2000, at time x=2 we have 4000.  

so that's an initial value of 1000 and a ratio of 2,

y = 1000 (2^x)

hope this !