Question

recursive function f(n+1)=1/3 f(n) if f (3)=9 what is f(1)

Answer 1

$f(n+1)=\dfrac{1}{3}f(n)\\ f(n)=3f(n+1)\\\\ f(2)=3\cdot9=27\\ f(1)=3\cdot27=81$