{ diff(x1, t) = 0, diff(x2, t) = (1*k3*k4*k14 + (-1)*k3*x4*k6*x2/(k5 + x2) + (-1)*k3*k8*x2 + (-2)*k3*(k9*x2^2 - k10*x5))/k3, diff(x3, t) = (1*k3*x4*k6*x2/(k5 + x2) + (-1)*k3*k7*x3)/k3, diff(x4, t) = 0/k3, diff(x5, t) = (1*k3*(k9*x2^2 - k10*x5) + (-1)*k3*k11*x5 + (-1)*k3*x4*k13*x5/(k12 + x5))/k3 }