Question

Let S be the subspace of R4 given by the solution set of the equations


-x2 + x3 - x4 = -x1 + 4 x4 and x1 - x3 = 3 x1 + x2 = x4

1. An example of a matrix for which S is the nullspace?


The answer was
1, -1, 1, -5
-2, -1, -1, 0
1, 0, -1, -1

but have no idea how help please lol