Question

If f(1) = 5 and f(x+1) =2f(x) then the value of f(7) is

Answer 1

\[f(1)=5\]
\[f(2)=2\times 5=10\]
\[f(3)=2\times 10=20\]

Answer 2

and in general
\[f(x)=5\times 2^{x-1}\]

Answer 3

making
\[f(7)=5\times 2^6\]