General form is ab^x
If (1, 7.5) is a point then:
ab^1 = 7.5
If (3, 16.875) is a point then:
ab^3 = 16.875
ab^3 can be rewritten as (ab)*b^2
Since we know that ab = 7.5, we can substitute:
7.5*b^2 = 16.875
b^2 = 9/4
b = 3/2
Now take b and plug in back into one of our old equations:
a(3/2)^x
Plug in (1, 7.5):
a*(3/2)^1 = 7.5
a = 5
So our general equation is: 5*(3/2)^x
where a = 5 and b = 3/2