For comparison with other CAS choose from: Axiom Derive Macsyma Mathematica Reduce
solve( {alpha* c1 - beta* c1
^
2 - gamma* c1*c2 + epsilon* c3 = 0, \
-gamma* c1*c2 + (epsilon+theta)* c3 - eta* c2 = 0, \
gamma* c1*c2 + eta* c2 - (epsilon+theta)* c3 = 0} ,{c3,c2,c1});
{c1 = c1, c2 = c1 (- epsilon alpha + c1 epsilon beta - theta alpha + c1 theta beta) - -------------------------------------------------------------------- - eta epsilon + c1 theta gamma , c3 = 2 c1 (- alpha eta + beta c1 eta - gamma c1 alpha + gamma c1 beta) - ---------------------------------------------------------------- - eta epsilon + c1 theta gamma }