Since the vectors are of the type (a, b, 0) grouping by x^2, x, 1 then taking a linear combination of these, I can tell a(1,0,0)^T + b(0,1,0) = (x^2, x, 1) and use it to determine if they span S. They DO!. On the other hand the coeff matriz [(1,0,0)^T (0,1,0)^T] is non singular so these vectors...