help with functions inside fsolve

hi guys, im new in matlab and i have this questions. im using fsolve for 3x3 non linear equations. so as far i can understand i define my system of equations as

function  f = func( x )
f(1)=a*2*x(1) - b*x(2) - exp(-x(1));
f(2)=-c*x(1) + 2*x(2) - d*exp(-x(2))];
end

but in the model the constants a to d depend in the values iterated of "x", for example, for each x(1) and x(2) i gonna have differents values of a to d so i define a new function like this

function  [a b c d] = const( x )
a=x(1)*3; 
b=x(2)*5;
c=x(1)+x(2);
d=x(1)/3;

so my question is, is it right to call the function const" from the function "func like this:

function  f = func( x )
[a b c d] = const ( x )
f(1)=a*2*x(1) - b*x(2) - exp(-x(1));
f(2)=-c*x(1) + 2*x(2) - d*exp(-x(2))];
end

in other hand, my equations are so complex, and i want to reduce the f(1) and f(2) defining a new fuction for example if i consider

f(1)=a*2*x(1) - b*x(2) - exp(-x(1)) =A - B - C
f(2)=-c*x(1) + 2*x(2) - d*exp(-x(2))]=D + E - F

and make a new function like this

 [A B C D E F] = fcont( x, a , b , c ,d )

A=a*2*x(1)
B=b*x(2)
C=exp(-x(1))
D=-c*x(1)
E=2*x(2)
F= d*exp(-x(2))

and finally have a func file that have inside two functions like this

function  f = func( x )
[a b c d] = const ( x )
[A B C D E F] = fconst( x, a , b , c ,d )
f(1)=A-B -C;
f(2)=-D + E -F;

is it well planned? or just i mess everything? i wait for your answers!!