{ diff(x1, t) = (1*k11*k3*k4 + (-3)*k11*k5*x1*(x3 + 3*x2 - (6*x3*x2 - 3*x2^2 + x3^2)^(1/2))/6)/k11,
  diff(x2, t) = ((-1)*k11*k5*x1*(x3 + 3*x2 - (6*x3*x2 - 3*x2^2 + x3^2)^(1/2))/6 + 1*k11*k6*((x3 + 3*x2 - (6*x3*x2 - 3*x2^2 + x3^2)^(1/2))/6)^(13/25)*((7*x3 - 3*x2 - (6*x3*x2 - 3*x2^2 + x3^2)^(1/2))/6)^(41/100) + (-1)*k11*2*k7)/k11,
  diff(x3, t) = 1*k11*k7*(1 - k8*((x3 + 3*x2 - (6*x3*x2 - 3*x2^2 + x3^2)^(1/2))/6)^k9*((7*x3 - 3*x2 - (6*x3*x2 - 3*x2^2 + x3^2)^(1/2))/6)^k10)/k11 }