I have a matrix $\displaystyle A$

$\displaystyle 2 4 1 1$

$\displaystyle 3 4 0 2$

$\displaystyle 1 2 1 2$

Now im trying to find a basis for the nullspace(A)

After applying GJ to A i get

$\displaystyle 1 0 0 4$

$\displaystyle 0 1 0 0$

$\displaystyle 0 0 1 3$

Now how would i go from this matrix to finding the single basis vector

b4 =

1

0

2

1

I don't understand how they went from the matrix to this vector. Any help would be greatly appreciated