Why would you think it possible or not? Did you try it?
x=@(t) 1+ t + 3*t^2 + 5*t^3 + 9*t^4;
y=@(t) 1+ t + 3*t^2;
z=@(t) x(t)-y(t)
syms t
z(t)
ans =
9*t^4 + 5*t^3
If your question is can you actually get something like this:
x(t)-y(t) = 5t^3 + 9t^4
I'm not really sure what you mean by that, or what is your goal.
