Dear Friends:

My original equation is

solve({(1-3*q2)*(1+lamda) = 0, r1*q1-2*r2*XA*(1+lamda) = 0, (1-2*q2)*q2-r2*XA^2 = 0, 1-3*q1+r1*XA = 0}, {XA, q1, q2, lamda})

The answer is

{XA = -1/r1, q1 = 0, q2 = RootOf(r2-r1*_Z+2*_Z^2)/r1, lamda = -1}, {XA = RootOf(-1+9*r2*_Z^2), q1 = 1/3+(1/3)*r1*RootOf(-1+9*r2*_Z^2), q2 = 1/3, lamda = (1/6)*(9*r2*r1*RootOf(-1+9*r2*_Z^2)+r1^2-6*r2)/r2}

Two questions:

1. Actually I want...

                     gama2 q2 - 2 gama1 XA=0

                    [-1] q1 + [1 - 2 q1] - C=0

              [-1] q2 + [1 - 2 q2] - C + gama2 XA=0