please help me in this 3 questions

4. (5 pts.) Let V be a vector space. Let 7: V - V be a linear transformation such that To T = 1. Show that {v, T(v) } is linearly dependent if and only if T(v) = tv. 5. Let A be an m x n matrix. Suppose that v is a column vector in F" and w is a row vector in Fm. (a) (5 pts.) Show that Av is a linear combination of the columns of A. (b) (5 pts.) Show that wA is a linear combination of the rows of A. 6. (5 pts.) Let V and W be vector spaces, and let T and U be nonzero linear transformations from V into W. If R(T) n R(U) = {0}, show that {7, U} is linearly independent in C(V, W)