k6*x12 - k5*x1 - k4*x1 + k3*x5*x13 
k21*x3 - k16*x2 - k22*x2 + k18*x9 - k31*x2 + k32*x10 - k17*x2*x13 + k15*x11*x13 
k13*x5 - k14*x3 - k8*x3 + k10*x12 - k21*x3 + k22*x2 + k7*x4*x13 - k9*x3*x13 
k8*x3 - k12*x4 + k11*x6 - k19*x4 + k20*x11 - k7*x4*x13 
k4*x1 - k2*x5 + k14*x3 - k13*x5 + k1*x6*x13 - k3*x5*x13 
k2*x5 + k12*x4 - k11*x6 - k1*x6*x13 
k33*x9 - k34*x7 - k28*x7 + k27*x10*x13 
k26*x10 - k30*x8 + k29*x11 - k25*x8*x13 
k23*x12 - k24*x9 - k18*x9 + k34*x7 - k33*x9 + k17*x2*x13 
k31*x2 + k28*x7 - k26*x10 - k32*x10 + k25*x8*x13 - k27*x10*x13 
k16*x2 + k19*x4 - k20*x11 + k30*x8 - k29*x11 - k15*x11*x13 
k5*x1 - k6*x12 - k10*x12 + k24*x9 - k23*x12 + k9*x3*x13 
k4*x1 + k2*x5 + k8*x3 + k16*x2 + k10*x12 + k18*x9 + k28*x7 + k26*x10 - k1*x6*x13 - k3*x5*x13 - k7*x4*x13 - k9*x3*x13 - k17*x2*x13 - k15*x11*x13 - k25*x8*x13 - k27*x10*x13 
2*x1 - k36 + x2 + x3 + x5 + 2*x7 + 2*x9 + x10 + 2*x12 + x13 
x1 - k37 + x2 + x3 + x4 + x5 + x6 + x7 + x8 + x9 + x10 + x11 + x12 
