T(n) = 2*T(n-1)
= 2*2*T(n-2)
= 2*2*2*T(n-3)
...
= 2n*T(n-n)
= 2n
Solving Recurrence Formulas
Another Example
T(0) => 1;
T(n) => 2*T(n-1);
use the above formulas repeatedly
T(n)= 2n
is a closed form solution