Obtain the extremals (if they exist) of the following problem of Lagrange with functional
I[x] = ∫[0,π/2] (ẁ2)^2 - (x2)^2 dt ,
subject to the following auxiliary and boundary conditions:
ẁ1 + ẁ2 + ẁ3 = 0, ẁ1 + 2ẁ3 = 0,
x1(0) = x2(0) = x3(0) = 0,
x1(π/2) = -π, x2(π/2) = 3π/2, x3(π/2) = π/2