I am working on several linear algebra problems and found myself stuck on two problems. Any helpful hints or suggestions on how to go about solving them will begreatly appreciated.

1) Given a 3 x 5 matrix and T(x)=Ax. Find range(T).

How do I find the range?

2) Let V be an inner product spae with a subspace W having B={w1,w2,...,wn} as an orthonormal basis. Show that the T(v)= the sumi=1 to n of<v,wi>wiis a linear transformation.