I know you probably would like people to address you more challenging questions, but this is not: I am having problems with stupid vectors(I admit it my questions are stupid...); let's assume A=(t; 5-t) and B=(s; -s), and let's assume I intend to see which one, if one, is a subspace of R2; i would say B is. But i am not sure. Moreover, consider 4 vectors V=(3; 2; 7) T=(1; -5; 1) Z=(0; -3, 1) P=(-1;3; 2) a basis for the linear space spanned by these vectors is formed by 2, 3 or 4 vectors, or none of the preceding?thanks a lot