k3*x3 + k5*x4 + k10*x8 - k2*x1*x2 - k6*x1*x5 - k9*x1*x7 
k3*x3 - k2*x1*x2 
k2*x1*x2 - k4*x3 - k3*x3 
k4*x3 - k5*x4 + k6*x1*x5 
k5*x4 + k8*x7 - k6*x1*x5 - k7*x5*x6 
k8*x7 - k7*x5*x6 
k10*x8 - k8*x7 - k9*x1*x7 + k7*x5*x6 
k9*x1*x7 - k10*x8 
x6 - k11 + x7 + x8 
x1 - k12 + x3 + x4 + x8 
x2 - k13 + x3 + x4 + x5 + x7 + x8 
