We are providing you solutions but you don't seem to be understanding them (your matrix question shows it), please try to understand our answers before creating more questions (most of them similar), you don't learn to use MATLAB having others doing the code for you, I guess you are in school so your teachers will evaluate your knowledge, we won't be there to do the code for you!
Using the symbolic toolbox:
solve(sym('exp(4)*x-3*exp(2)*x=-2'))
solve(sym('atan(x) + atan(2*x)=0'))
s=solve(sym('x-2*y+3*z=10'), sym('2*x-y-4*z=8'),sym('2*x+y-z=15'));
double([s.x s.y s.z])' %from top to bottom x y z
