Question

Iff (1) = 7and f(n) = - 2f(n - 1) - 1 then find the value of f(5).

Answer 1

`\begin{gathered} f(2)=-2\cdot f(2-1)-1=-2\cdot f(1)-1=-2\cdot7-1=-14-1=-15 \\ f(3)=-2\cdot f(3-1)-1=-2\cdot f(2)-1=-2\cdot(-15)-1=30-1=29 \\ f(4)=-2\cdot f(4-1)-1=-2\cdot f(3)-1=-2\cdot(29)-1=-58-1=-59 \\ f(5)=-2\cdot f(5-1)-1=-2\cdot f(4)-1=-2\cdot(-59)-1=118-1=117 \end{gathered}`