Given a set of vectors v1 v2 v3 a vector b is in Spanv1 v2 v
     Given a set of vectors {v_1, v_2, v_3}, a vector b is in Span{v_1, v_2, v_3} if and only if the linear system with corresponding augmented matrix (v_1 v_2 v_n | b) is consistent.  If u and v are vectors in R^2, then u + v corresponds to the fourth vertex of the parallelogram whose other three vertices are u, u - v, and v.  If two vectors are scalar multiples of eachother, then the two vectors lie on the same line.  Given two vectors v_1 and v_2 in R^n, an example of a linear combination of these two would be 281v_2.   
  
  Solution
a) it is ture because it will happen only in case of a solution
b)true because opposite sides are parallel
c) false , because same line points shows parallel only
d) true it is represntation of R^n for two

