Hello,
Some idea maybe of some interest...
First replace the constant part of equation by one parameter name.
This gives the following system:
sys:[
m1=k11-k71^2/k77,
m2=k21-(k72*k71)/k77,
m3=k22-k72^2/k77,
m4=k31-(k71*k73)/k77,
m5=k32-(k72*k73)/k77,
m6=k33-k73^2/k77,
m7=k41-(k71*k74)/k77,
m8=k42-(k72*k74)/k77,
m9=k43-(k73*k74)/k77,
m10=k44-k74^2/k77,
m11=k51-(k71*k75)/k77,
m12=k52-(k72*k75)/k77,
m13=k53-(k73*k75)/k77,
m14=k54-(k74*k75)/k77,
m15=k55-k75^2/k77,
m16=k61-(k71*k76)/k77,
m17=k62-(k72*k76)/k77,
m18=k63-(k73*k76)/k77,
m19=k64-(k74*k76)/k77,
m20=k65-(k75*k76)/k77,
m21=k66-k76^2/k77,
b3*k21-b2*k31+a3*k51-a2*k61=(-k71),
b3*k22-b2*k32+a3*k52-a2*k62=(-k72),
b3*k23-b2*k33+a3*k53-a2*k63=(-k73),
b3*k24-b2*k34+a3*k54-a2*k64=(-k74),
b3*k25-b2*k35+a3*k55-a2*k65=(-k75),
b3*k26-b2*k36+a3*k56-a2*k66=(-k76),
b3*k27-b2*k37+a3*k57-a2*k67=(-k77)
];
after what you can use "eliminate".
sys1:eliminate(sys,[k11,k21,k22,k31,k32,k33,k41,k42,k43,k44,k51,k52,k53,k54,k55,k61,k62,k63,k64
,k65,k66,k71,k72,k73,k74,k75,k76]);
the result is:
[(k77-a2*k67+a3*k57-b2*k37+b3*k27)^134217728]
Laurent.