Solve system of equations give wrong solution

Hi guys and thanks in advance. I am trying to solve a system of nonlinear equations as shown in the code below using vpasolve. However, when I run the code it gives me wrong answers

syms atx btx ctx aGA bGA cGA
        eq1=atx+btx;
        eq2=atx+btx*exp(-105*ctx);
        eq3=atx+btx*exp(-180*ctx);
        eq4=aGA+bGA;
        eq5=aGA+bGA*exp(-105*cGA);
        eq6=aGA+bGA*exp(-180*cGA);
        eqns=[eq1==BMDT, eq2==AMDT1, eq3==AMDT2];    % Where BMDT and AMDT1 and AMDT2 are change in every run but for example take them as 204, 192.61 and 177.6 respectiviely.
        eqns2=[eq4==BMDA, eq5==AMDA1, eq6==AMDA2];   % Where BMDA and AMDA1 and AMDA2 are change in every run but for example take them as and 2772.4, 2060.1 and 1965.6 respectiviely.
        S = vpasolve(eqns, [atx btx ctx]);
        S2 = vpasolve(eqns2, [aGA bGA cGA]);
        at= S.atx;
        bt= S.btx;
        ct= S.ctx;
        aA= S2.aGA;
        bA= S2.bGA;
        cA= S2.cGA;

What possible could be wrong knowing that sometimes it gives correct answer while other time I doesn't, and what is a possible soultion for it

Answer 1

[Jesús Zambrano]

Hi Abdullah,

When using vpasolve, try (if possible) to include a good guess of the solution (X0). The X0 is optional, if no value is used, the numerical solver makes its own internal choices.