Its Spring Break so I've decided to get and stay caught up

Determine if the given set is a subspace ofPn, for an appropriate value of n

1. All polynomials of the formp(t) = at^2, where a is inR

2. All Polynomials of the formp(t) = a + t^2, where a is inR

As always an explination is much more important than an answer.

Thanks