fsolve or fminsearch is not able to provide constant values in answer of non linear equations by changing initial guesses. Kindly solve these equations by using either fsolve or any other suitable solver

(6.2975e-11)*((1-x(1)-x(2)-x(3))*((0-3.*x(1)-7.*x(2))^3)*((1+0+12*x(1)+4*x(2)+4*x(3))^8))) - (((4.*x(1)+x(3))^4)*((2.*x(3))^8));

(0.0184*((1-x(1)-x(2)-x(3))*((0-3.*x(1)-7.*x(2))^7)*((1+0+12*x(1)+4*x(2)+4*x(3))^8))) - (((4*x(1))^4)*((2.*x(3))^12));

((4.3202e+16)*((1-x(1)-x(2)-x(3))*((1+0+12*x(1)+4*x(2)+4*x(3))^4))) - (((4.*x(1)+x(3)))*((8.*x(1)+12.*x(2)+x(3))^2)*(2.*x(3))*(1+0+12*x(1)+4*x(2)+4*x(3)));

[Torsten]

What makes you think your system has a unique solution ?

Best wishes

Torsten.

[Walter Roberson]

The first subexpression

   (6.2975e-11)*((1-x(1)-x(2)-x(3))*((0-3.*x(1)-7.*x(2))^3)*((1+0+12*x(1)+4*x(2)+4*x(3))^8)))

has an extra ")"

On the third line, the first subexpression also has an extra ")"

(4.3202e+16)*((1-x(1)-x(2)-x(3))*((1+0+12*x(1)+4*x(2)+4*x(3))^4))) 

Answer 1

[Walter Roberson]

Amongst numerous other solutions:

Your system is satisfied by x(3) = 0, x(1) = 1 - x(2), for all x(2). Therefore depending on what your initial x(2) is you might get out a different solution that is a member of this family.

You have a mix of 16th order, 12th order, and (4th order plus a linear root) for your equations. You should not be surprised that there are multiple solutions.