> solve( {  3*k*u[2] - 2*k*u[3]                                         
>                  = 0,                  -2*k*u[2] +5*k*u[3] - 3*k*u[4] 
>                                       = F,                            
>       - 3*k*u[3] + 5*k*u[4] - 2*k*u[5]                     = 0,       
>                                               - 2*k*u[4] + 3*k*u[5]   
>                  = 0},     {u[2], u[3], u[4], u[5] });

                 9 F          11 F         33 F         27 F
         {u[5] = ----, u[2] = ----, u[3] = ----, u[4] = ----}
                 20 k         20 k         40 k         40 k

> 
> 
