 
 
 
 
 
 
 
 
Answer: Maple only allows assignment to names. subs does not work in this case since it is strictly syntactic. The easiest thing to do is to use rem as follows:
> p;
                  2       3       4        5        6         7
     1 + 3 x + 9 x  + 27 x  + 81 x  + 243 x  + 729 x  + 2178 x
                8          9
        + 6561 x  + 19683 x
> rem(p,x^6,x);
                                2       3       4        5
                   1 + 3 x + 9 x  + 27 x  + 81 x  + 243 x
Related help pages include: rem.