I'm not really sure how to prove this is a linear transformation. I couldn't find a definition for a linear transformation either which made the problem more confusing.Quote:

Let be given by . This is projection from 3-space onto the xy-plane. Show that T is a linear transformation. What is the matrix associated to T?

I also don't know what it means by "matrix associated to T". Is this all it wants:

?

Help would be appreciated!