k13 - k2*x1*x2 - k16*x1*x8 
k14*k19 - k15*x2 + k8*x10^2 - k2*x1*x2 - k6*x2*x9 - k12*x2*x12 
k8*x10^2 + k2*x1*x2 - k3*x3*x4 
k5*x6*x7 - k3*x3*x4 - k7*x4*x10 - k11*x4*x9 
k3*x3*x4 - k4*x5*x6 + k9*x9*x11 
k16*x1*x8 - k5*x6*x7 - k4*x5*x6 
x6*(k4*x5 - k5*x7) 
k4*x5*x6 + k5*x6*x7 - k16*x1*x8 
k16*x1*x8 - k6*x2*x9 - k11*x4*x9 - 2*k10*x9^2 - k9*x9*x11 
k6*x2*x9 - 2*k8*x10^2 - k7*x4*x10 
k7*x4*x10 + k12*x2*x12 - k9*x9*x11 
k11*x4*x9 - k12*x2*x12 
x6 - k21 + x8 
x4 - k22 + x5 + x7 + x11 + x12 
