The first one can be expressed as a vector (check it though)
Second one can be developed by a basis
so to check whether are linearly independent and therefore form a basis you should develop them:
so get it to reduced row echelon form and you'll see if the vectors are linearly independent or not.
In the third one all you should to is check whether it's a subspace or not it's rather easy.
you need to check if and then and