{ diff(x2, t) = ((-1)*k13*(k14*x1*x2 - k15*x11) + 1*k13*k10*k26 + (-1)*k13*k10*x2)/k13,
  diff(x3, t) = ((-1)*k13*(k16*x3*x5 - k17*x4) + 1*k13*k18*x4 + (-1)*k13*k19*x3 + 1*k13*k25*x11)/k13,
  diff(x4, t) = (1*k13*(k16*x3*x5 - k17*x4) + (-1)*k13*k18*x4)/k13,
  diff(x5, t) = ((-1)*k13*(k16*x3*x5 - k17*x4) + 1*k13*k23*x6)/k13,
  diff(x6, t) = (1*k13*k18*x4 + (-1)*k13*(k20*x6*x7 - k21*x8) + 1*k13*k22*x8 + (-1)*k13*k23*x6)/k13,
  diff(x7, t) = ((-1)*k13*(k20*x6*x7 - k21*x8) + 1*k13*k24*x9)/k13,
  diff(x8, t) = (1*k13*(k20*x6*x7 - k21*x8) + (-1)*k13*k22*x8)/k13,
  diff(x9, t) = (1*k13*k22*x8 + (-1)*k13*k24*x9)/k13,
  diff(x10, t) = 0,
  diff(x11, t) = (1*k13*(k14*x1*x2 - k15*x11) + (-1)*k13*k25*x11)/k13 }