1. The problem statement, all variables and given/known data The only functions with a constant doubling time are the exponential functions P0ekt with k > 0. Show that the doubling time of linear function f(t) = a(t) + b at time t0 is t0 + b/a. 2. Relevant equations n/a 3. The attempt at a solution With initial time t0, P = at0 + b At some time t, P is doubled: at + b = 2P t = (2P - b)/a Plug in P and simplify: t = (2at0 + b)/a t = 2t0 + b/a What am I doing wrong?