Optimal control
So
d^2 p
dt^2 =^2
dx
dt=^2 p(t)/^2 =p(t).
It is a second order linear equation with characteristic polynomial
λ^2 1 = 0 .Using the general solution
p(t)=c 1 exp(t)+c 2 exp( t), p(T)= 0
On the other hand
dp
dt(^0 )=^2 x(^0 )=^2 x^0
c 1 = 2 x 0 e T/
eT+e T
, c 2 = 2 x 0 eT/
eT+e T
x(t) =^1
2
dp
dt
=x 0 e
T t+et T
eT+e T