In[]:=
u1[x_]:=0.5Log[x]+0.8Log[4]​​Plot[u1[x],{x,0,10}]
Out[]=
In[]:=
u2[x_]:=0.5Log[x]+0.8Log[6]​​Plot[{u2[x],u1[x]},{x,0,10}]
Out[]=