Suppose that A elementof Mm times nR For what relationship b
     Suppose that A elementof M_m times n(R). For what relationship between m and n will it be necessarily true that  Null (A) is nontrivial and  the columns of A do not span R^m. 
  
  Solution
solution : given that A berwelong to Matrices of order m*n over set of real number R.
implise that Matrx A is also m*n ,where m is number of row and n is number of column .
so (b) is true a s column of A do not span Rm.

