{ diff(x1, t) = (1*k14*k1 + 1*k14*k2*k3 + (-1)*k14*k4*x1^k5/(k6^k5 + x1^k5) + 1*k15*k7*x2^k8*x1^k13/((k9^k8 + x2^k8)*(k10^k13 + x1^k13)) + 1*k15*k11*x2 + (-1)*k14*k12*x1)/k14,
  diff(x2, t) = (1*k14*k4*x1^k5/(k6^k5 + x1^k5) + (-1)*k15*k7*x2^k8*x1^k13/((k9^k8 + x2^k8)*(k10^k13 + x1^k13)) + (-1)*k15*k11*x2)/k15 }