For a system of vectors U = {(1,2, 6); (0, -1, -5);(2,3,7); (1,0,-4) } .
a. Find the number of dimensions and a basis W of the subspace generated by the vector system U .
b. Find the parameter k to
u = (2,3, k^2+1) is a linear combination of W , and it follows that [ ]W
u .