Given f(x)= ab^2 what is the value of a in the following table?

We have;
[tex]f(x)=ab^x[/tex]We want to obtain the value of a given the table.
Luckily we can obtain the value of a since;
[tex]\begin{gathered} f(x)\text{ if x=0, i.e } \\ f(0)=a(b^0)=a\times1=a \end{gathered}[/tex]Thus a is the value of f(x) when x = 0.
Let's get the value of f(x) when x = 0 from the table.
[tex]\text{from the table at, at x =0 , f(x)= a = 500}[/tex]Therefore, a = 500