Transform the given expression to the canonical form to prove that they are, in fact, polynomials.
 .
 .
 .

Proof. We use the binomial theorem,

Proof. Recalling a previous exercise, we have

Proof. Again, we recall a previous exercise to obtain,
in (a) the second step should be (m k) instead of (m n) right?
Hi. Is there an addition sign (+) missing in the 5th line in part c? The line that has “(distributing)” to the right of it.
Jacare, yes you are right!