MATLAB: How to substitute an syms variable into known value and evaluate the result of the same equation that contain it

Question

i'm tying to generate a general equation for Bezier curve in polynomial form , differentiate it, then substitute the value of u by 0 or 1 in the general equation but i don't know how

% u incremental value
n=input('input the number of control points = ');
k= n-1
m=1;
   for  i=0:1:k;
       w=1;
       syms u 
        r(w,m)=factorial (k)/(factorial(i)*factorial(k-i))*u.^i*(1-u).^(k-i)
      w=w+1
      m=m+1
   end;
   syms u
   d=diff (r)
   syms u
   f= diff(r,2)
for u=1
    g1=(r)
end

Answer 1

g1 = subs(r, u, 1);
g0 = subs(r, u, 0);